Sun Microsystems, Inc. v. Network Appliance, Inc. (710 F. Supp. 2d 925, 2008)

United States District Court for the Northern District of California 2008-12-22

Citations

Full opinion text

ORDER CONSTRUING CLAIM TERMS OF THE '987, '855, '012 AND '787 PATENTS

ELIZABETH D. LAPORTE, United States Magistrate Judge.

On November 10, 2008, the Court held a hearing to construe the disputed terms of United States Patent Numbers 5,124,987 (the “'987 patent”), 5,430,855 (“'855 patent”), 5,632,012 (“'012 patent”), and 6,421,-787 (“'787 patent”) pursuant to Markman v. Westview Instruments, Inc., 517 U.S. 370, 116 S.Ct. 1384, 134 L.Ed.2d 577 (1996). Having read the papers and considered the arguments of counsel and the relevant legal authority, the Court hereby rules as follows.

1. BACKGROUND

On October 29, 2007, Sun Microsystems Inc. (“Sun”) filed its complaint against Network Appliance Inc. (“NetApp”) for Patent Infringement, Unfair Competition Under the Lanham Act and Unfair Competition under California Business and Professions Code § 17200. On November 2, 2007, Sun filed its First Amended Complaint, alleging that NetApp infringes the four patents noted above, as well as United States Patent Nos. 6,049,528 and 5,721,937 (collectively, the “Sun patents”), through its Fabric Attached Storage, V-series and NearStore products.

On December 21, 2007, NetApp filed its Answer and Counterclaim to First Amended Complaint. NetApp denies infringing any of the Sun patents and alleges that Sun infringes United States Patent Numbers 6,574,591 (the “'591 patent”), 6,868,-417 (the “'417 patent”), 7,107,385 (the “'385 patent”), and 7,130,873 (the “'873 patent”). NetApp also alleges that Sun violated the Lanham Act and California Business and Professions Code § 17200 et seq. On January 14, 2008, Sun filed its Reply to NetApp’s Answer and Counterclaims, denying the allegations and asserting a number of affirmative defenses and counterclaims.

On February 19, 2008, NetApp filed its Supplemental Answer and Counterclaims, expanding the allegations of infringement to include United States Patent Number 7,313,720 (the “'720 patent”) in addition to the patents noted above (collectively, the “NetApp patents”). On March 7, 2008, Sun filed its reply to NetApp’s Supplemental Answer and Counterclaims.

The parties now seek construction of five disputed terms contained in the Sun patents.

II. LEGAL STANDARD

In construing claims, the court must begin with an examination of the claim language itself. The terms used in the claims are generally given their “ordinary and customary meaning.” See Phillips v. AWH Corp., 415 F.3d 1303, 1312-13 (Fed.Cir.2005); see also Renishaw PLC v. Marposs Societa’ per Azioni, 158 F.3d 1243, 1248 (Fed.Cir.1998) (“The claims define the scope of the right to exclude; the claim construction inquiry, therefore, begins and ends in all cases with the actual words of the claim.”). This ordinary and customary meaning “is the meaning that the terms would have to a person of ordinary skill in the art in question at the time of the invention .... ” Phillips, 415 F.3d at 1313. A patentee is presumed to have intended the ordinary meaning of a claim term in the absence of an express intent to the contrary. York Products, Inc. v. Central Tractor Farm & Family Ctr., 99 F.3d 1568, 1572 (Fed.Cir.1996).

Generally speaking, the words in a claim are to be interpreted “in light of the intrinsic evidence of record, including the written description, the drawings, and the prosecution history, if in evidence.” Teleflex, Inc. v. Ficosa North Am. Corp., 299 F.3d 1313, 1324-25 (Fed.Cir.2002) (citations omitted); see also Medrad, Inc. v. MRI Devices Corp., 401 F.3d 1313, 1319 (Fed.Cir.2005) (court looks at “the ordinary meaning in the context of the written description and the prosecution history”). “Such intrinsic evidence is the most significant source of the legally operative meaning of disputed claim language.” Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed.Cir.1996).

With regard to the intrinsic evidence, the court’s examination begins with the claim language. See id. Specifically, “the context in which a term is used in the asserted claim can be highly instructive.” Phillips, 415 F.3d at 1314. As part of that context, the court may also consider the other patent claims, both asserted and unasserted. Id. For example, as claim terms are normally used consistently throughout a patent, the usage of a term in one claim may illuminate the meaning of the same term in other claims. Id. The court may also consider differences between claims as a guide to understanding the meaning of particular claim terms. Id.

Second, the claims “must [also] be read in view of the specification, of which they are a part.” Id. at 1315. When the specification reveals a special definition given to a claim term by the patentee that differs from the meaning it would otherwise possess, the inventor’s lexicography governs. Id. at 1316. Indeed, the specification is to be viewed as the “best source” for understanding a technical term, informed as needed by the prosecution history. Id. at 1315. As the Federal Circuit stated in Phillips, the specification is “the single best guide to the meaning of a disputed term,” and “acts as a dictionary when it expressly defines terms used in the claims or when it defines terms by implication.” 415 F.3d at 1321.

Limitations from the specification, however, such as from the preferred embodiment, cannot be read into the claims absent a clear intention by the patentee to do. Altiris v. Symantec Corp., 318 F.3d 1363, 1372 (Fed.Cir.2003) (“resort to the rest of the specification to define a claim term is only appropriate in limited circumstances”); Teleflex, 299 F.3d at 1326 (“The claims must be read in view of the specification, but limitations from the specification are not to be read into the claims.”) (citations omitted); CCS Fitness, Inc. v. Brunswick Corp., 288 F.3d 1359, 1366 (Fed.Cir.2002) (“a patentee need not describe in the specification every conceivable and possible future embodiment of his invention”).

“[T]here is sometimes a fine line between reading a claim in light of the specification, and reading a limitation into the claim from the specification.... [Aittempting to resolve that problem in the context of the particular patent is likely to capture the scope of the actual invention more accurately than either strictly limiting the scope of the claims to the embodiments disclosed in the specification or divorcing the claim language from the specification.” Decisioning.com, Inc. v. Federated Dept. Stores, Inc., 527 F.3d 1300, 1307-08 (Fed.Cir.2008) (quoting Comark Comm’ns, Inc. v. Harris Corp., 156 F.3d 1182, 1186 (Fed.Cir.1998)). There is therefore “no magic formula or catechism for conducting claim construction,” and the court must “read the specification in light of its purposes in order to determine whether the patentee is setting out specific examples of the invention to accomplish those goals, or whether the patentee instead intends for the claims and the embodiments in the specification to be strictly coextensive.” Id. (internal citations omitted).

Finally, as part of the intrinsic evidence analysis, the court “should also consider the patent’s prosecution history, if it is in evidence.” Phillips, 415 F.3d at 1317. The court should take into account, however, that the prosecution history “often lacks the clarity of the specification” and thus is of limited use for claim construction purposes. Id.

In most cases, claims can be resolved based on intrinsic evidence. See Vitronics, 90 F.3d at 1583. Only if an analysis of the intrinsic evidence fails to resolve any ambiguity in the claim language may the court then rely on extrinsic evidence, such as expert and inventor testimony, dictionaries, and learned treatises. See Vitronics, 90 F.3d at 1583 (“In those cases where the public record unambiguously describes the scope of the patented invention, reliance on any extrinsic evidence is improper”). “Within the class of extrinsic evidence, the court has observed that dictionaries and treatises can be useful in claim construction.” Phillips, 415 F.3d at 1318. While expert testimony can be useful to a court for a variety of purposes, eonclusory assertions by experts are not useful to a court. Id. The court generally views extrinsic evidence as less reliable than the patent and its prosecution history in determining how to read claim terms, even if though consideration is within the court’s sound discretion. See id. at 1318-19.

III. DISCUSSION

The parties dispute five terms contained in four of the Sun patents: (1) “first available memory space” in the '987 patent; (2) “means, responsive to the receipt of a stream of data records from said associated data processor, for writing said received stream of data records in available memory space in one of said disk drives” in the '855 patent; (3) “means responsive to said reading of said memory controller for periodically verifying the integrity of data currently stored in each of said identified dedicated partitions” and (4) “means for reading data in each of said identified dedicated partitions” in the '012 patent; and (5) “active links between said active nodes” in the '787 patent. Following the November 10, 2008, hearing, the parties submitted a Joint Table of Final Proposed Constructions for the Sun patents.

A. '987 Patent

The '987 patent, “Logical Track Write Scheduling System for a Parallel Disk Drive Array Data Storage Subsystem,” is directed to a data storage system. The data storage subsystem stores data on a number of small hard disk drives, but emulates the format and operation of a large form factor disk drive: “This invention relates to an inexpensive, high performance, high reliability parallel disk drive array data storage subsystem that includes an efficient data storage management system to dynamically map virtual data storage devices to logical data storage devices and schedule the writing of data on these devices.” '987 patent, col. 1:7-12.

1. “First available memory space”

Disputed Claim Term: “first available memory space” ('987 patent, claims 9 and 57)_

NetApp’s

“one or more logical tracks, each of which must be empty, ie., recognized by the system as available free space”

construction_

“one or more empty logical tracks each of which is empty, ie., one or more empty stripes each of which is empty”

_“empty” means “available to be written to”

The parties agree on the wording of the construction of “first available memory space” as “one or more logical tracks, each of which is empty,” but dispute whether “empty” means “recognized by the system as available free space,” as NetApp contends, or “available to be written to,” as Sun proposes. The dispute centers on the question of whether the obsolete data must go through a process of being tagged as obsolete and the logical track thus recognized as available free space in order for the track to be available to be written to.

To begin its analysis, the Court first turns to the claims themselves. The term “first available memory space” appears in claims 9 and 57 of the '987 patent:

9. In a disk memory system, having a plurality of disk drives, a number of said plurality of disk drives being configured into at least two redundancy groups, each redundancy group consisting of at least two disk drives, a method of storing data records for at least one associated data processor comprising the steps of:

selecting, in response to the receipt of a stream of data records from said associated data processor, first available memory space in one of said redundancy groups to store said received stream of data records thereon;

writing said received stream of data records and redundancy data associated with said received stream of data records in said selected first available memory space in said selected redundancy group;

writing, in response to the subsequent receipt of modifications to one of said data records stored in said first available memory space in said selected redundancy group from said associated data processor, said modified data record, exclusive of the rest of said received stream of data records and said redundancy data associated with said received stream of data records written in said first available memory space, in second available memory space in one of said redundancy groups by including said modified data record with a stream of data records subsequently received for said step of writing; and

converting said first available memory space used to store said originally received data record to available memory space.

57. In a disk memory system having a plurality of disk drives, a number of said plurality of said disk drives configured into at least two redundancy groups, each redundancy group consisting of n + m disk drives, where n and m are both positive integers, with n being greater than 1 and m being equal to or greater than 1, for storing data records for at least one associated data processor comprising the steps of:

storing, in response to the receipt of n streams of data records from said associated data processor, said n received streams of data records;

generating m redundancy segments using said n received streams of data records;

selecting one of said redundancy groups having first available memory space, addressable at the same relative address for each of said n+m disk drives, for storing said n received streams of data records and said m generated redundancy segments;

writing said n received streams of data records and said m redundancy segments on said n + m disk drives in said first available memory space in said selected redundancy group, each stream of data records and each redundancy segment at said relative address on a respective one of said n+m disk drives;

writing, in response to the subsequent receipt of modifications to one of said data records, stored at said relative address on one of said n+m disk drives in said first available memory space in said selected redundancy group, from said associated data processor, said modified data record, exclusive of the rest of said n received streams of data records and said m redundancy segments associated with said n received streams of data records written in said first available memory space, in second available memory space in one of said redundancy groups, exclusive of said relative address on said one of said n + m disk drives in said selected redundancy group by including said modified data record with n streams of data records subsequently received for said step of writing; and

converting said first available memory space, addressable at said relative address on said one of said n+m disk drives in said selected redundancy group, used to store said originally received data record to available memory space.

'987 patent, col. 23:40-24:3, 31:53-32:57 (emphasis added).

The claim language teaches that the “first available memory space” is a space in a redundancy group selected as the location for writing the received streams of data records and their associated redundancy information. Looking to the specification for further guidance, the specification states that “[e]ach redundancy group, also called a logical disk drive, is divided into a number of logical cylinders,” and “[e]ach logical track is comprised of N + M physical tracks, one physical track from each disk drive in the redundancy group.” '987 patent, col. 3:50-54; 3:55-57.

In the “Solution” section of the specification, the patent describes the logical track write scheduling system of the claimed invention:

This system avoids the parity update problem of the prior art by never updating the parity in a data redundancy group. Instead, all new or modified data is written on empty logical tracks and the old data is tagged as obsolete. The resultant “holes” in the logical tracks caused by old data are removed by a background free-space collection process that creates empty logical tracks by collecting valid data into previously emptied logical tracks....

The original, unmodified data is simply flagged as obsolete. Obviously, as data is modified, the redundancy groups increasingly contain numerous virtual tracks of obsolete data. The remaining valid virtual tracks in a logical cylinder are read to the cache memory in a background “free space collection” process. They are then written to a previously emptied logical cylinder and the “collected” logical cylinder is tagged as being empty.

'987 patent, col. 3:33-41, 5:13-21 (emphasis added). The patent specification thus describes a write process whereby new or modified data is written on empty logical tracks, and old data is tagged as obsolete and removed by a background free-space collection process that creates empty logical tracks. In the free space collection process, the valid data is read to the cache memory, “then written” to a previously emptied logical cylinder and the collected logical cylinder is tagged as being empty, so that it can be written to. Id. at 5:13-21. See also id. at 5:57-63 (Detailed Description of the Drawing: “all new or modified data is written on empty logical tracks and the old data is tagged as obsolete. The resultant ‘holes’ in the logical tracks caused by old data are removed by a background free-space collection process that creates empty logical tracks by collecting valid data into previously emptied logical tracks.”); 20:64-70 (Free Space Collection: “In order to create completely empty logical cylinders for destaging, valid data in partially valid cylinders must be read into cache memory 113 and rewritten into new previously emptied logical cylinders.”). The plain language of the specification thus favors NetApp’s proposed construction requiring the logical tracks to be “tagged as being empty” and thereby recognized by the system as available free space.

Sun contends that NetApp’s proposed construction improperly reads the “free space collection process” into the claim term. The specification, however, describes “the present invention,” whereby “holes” in the logical tracks caused by old data are removed by a free-space collection process that creates empty logical tracks. '987 patent, col. 5:50, 59-62. Reading the claim in light of the specification, the Court concludes that one of ordinary skill in the art would understand empty logical tracks to have undergone a process by which old data has been tagged obsolete and the logical track is recognized as empty. By contrast, Sun’s proposed construction of “empty” as “available to be written to” is vague with respect to whether the old, unmodified data has been tagged as obsolete and the logical tracks thus recognized as being empty.

The parties also dispute whether the term requires writing only to empty logical tracks and never writing to logical tracks that are not empty. As Sun conceded, whenever claim 9 or 57 is practiced, those claims require writing to an empty logical track. However, the competing claims constructions proposed by the parties do not require the Court to decide an issue that emerged at the hearing: whether an accused product must practice exclusively the method of claims 9 and 57 to infringe or, as Sun characterizes the dispute, whether an accused system that fully practices the claimed method most of the time nevertheless does not infringe the patent if it ever practices a different method. The Court does, however, make the following observations. The express language of these method claims by itself does not compel NetApp’s proposed limitation that would require an accused product to always practice these claims in order to infringe. For example, claim 9 is a method claim as recognized by dependent claims 10 through 12 (“The method of claim 9 further comprising ... ”). The claim preamble specifies the configuration of the system in which the method operates, i.e., “[i]n a disk memory system.” NetApp suggested for the first time at the hearing that the preamble of claim 9 imports the limitation of claim 1 and other apparatus and memory system claims in the patent. Even assuming (without deciding) that the preamble is a limitation, see NetApp Suppl. Cl. Const. Br. at 4 n. 1, the preamble only describes a system of multiple disk drives configured into two or more redundancy groups each consisting of at least two disk drives, without stating whether the method must be exclusive. Furthermore, the claim 9 preamble does not refer to “[t]he system of claim 1,” unlike, e.g., claims 2, 4, or 8. Sun is correct that an accused product need not always practice a method to infringe. See Bell Commun. Research, Inc. v. Vitalink Commun., 55 F.3d 615, 622-23 (Fed.Cir.1995).

Even though the claim language by itself would not compel NetApp’s interpretation, there is strong support for it in the specification and prosecution history. The specification makes clear that the invention itself, unlike the prior art, never updates parity data in the redundancy group and avoids the negative impact on performance in the prior art, using strong and unequivocal language:

“A performance improvement is obtained by eliminating redundancy data updates in the redundancy group by writing modified virtual track instances into previously emptied logical tracks and marking the data contained in the previous virtual track instance location as invalid. Logical cylinders containing a mixture of valid and invalid virtual tracks are emptied by writing all the valid virtual tracks into a previously emptied logical cylinder as a background process.” '987 patent, Abstract (emphasis added);

“This system avoids the parity update problem of the prior art by never updating the parity in a data redundancy group.” Id. at 3:33-37 [Solution] (emphasis added);

“Thus, all redundancy data creation, writing and free space collection occurs in background, rather than on-demand processes. This arrangement avoids the parity update problem of existing disk array systems and improves the response time versus access rate performance of the data storage subsystem by transferring these overhead tasks to background processes.” Id. at 5:21-28 [Solution] (emphasis added);

“The data storage subsystem of the present invention uses a plurality of small form factor disk drives in place of a single large form factor disk drive to implement an inexpensive, high performance, high reliability disk drive memory that emulates the format and capability of large form factor disk drives. This system avoids the parity update problem of the prior art by never updating the parity. Instead, all new or modified data is written on empty logical tracks and the old data is tagged as obsolete.” Id. at 5:55-59 [Detailed Description of the Drawing] (emphasis added).

NetApp also relies on excerpts from the prosecution history to demonstrate that the applicants made a clear and unambiguous disavowal of claim scope by distinguishing the invention from the prior art disk array systems as “never updating parity in any redundancy group at any time.” NetApp Br. re Pros. Hist, at 2-3 (quoting '987 Prosecution History, Sept. 23, 1991 Amendment at 7 (NAB0013338)) (emphasis added). The applicants’ statements were made in response to the examiner’s objection to the specification and rejection of the claims noting that the written description was “unclear why writing data to a new location is an advantage. This simply changes which parity bits need to be regenerated.” Id. at 3 (NAB0013334). While the applicants’ statements in the prosecution history arguably do not by themselves amount to a clear and unambiguous statement that a system must always practice the claimed method in order to practice the patent, they lend further support to the strong language in the specification describing the featxxre of the invention as a whole, and thus may well limit the scope of the invention to require always writing only to an empty track. At this juncture, however, the Court reserves this question.

The briefs submitted by the parties raised a dispute as to whether “first available memory space” could include more than one logical track. During oral argument, however, NetApp conceded that there was no dispute about whether “first available memory space” could be construed as one or more logical tracks, but sought clarification that each of the tracks must be empty. Sun’s proposed construction, “each of which is empty,” also reflects this understanding, and the Court construes the term to reflect that each logical track is empty.

With respect to Sun’s proposal that “empty logical tracks” be further construed as “i.e., one or more empty stripes, each of which is empty,” NetApp argued that every logical track is a stripe, but not every stripe is a logical track. NetApp was concerned that the jury would be confused by using the terms stripe and logical track interchangeably. Other than offering expert opinion that a logical track is the same as a stripe in the context of this patent, Sun has not demonstrated that logical track should always be construed as a stripe. The Court declines to include the phrase “i.e., one or more empty stripes.”

For the reasons set forth above, the Court adopts NetApp’s proposed construction of “first available memory space” as “one or more logical tracks, each of which must be empty, i.e., recognized by the system as available free space.”

B. '855 Patent

The '855 patent, “Disk Drive Array Memory System Using Nonuniform Disk Drives,” is directed to a data storage subsystem that emulates the format of a large form factor disk drive. This patent focuses on enabling the system to work with a set of nonuniform small form factor disk drives, so that the small form factor disk drives do not need to share common physical characteristics such as track capacity and disk rotational speed. '855 patent, col. 1:41-51,1:58-2:22.

2. “Means, responsive to the receipt of a stream of data records from said associated data processor, for writing said received stream of data records in available memory space in one of said disk drives”

Disputed Claim Term: “means, responsive to the receipt of a stream of data records from said associated data processor, for writing said received stream of data records in available memory space in one of said disk drives” ('855 patent, claim 1)_

NetApp’s

This term is subject to 35 U.S.C. § 112, ¶ 6.

Function: “writing said received stream of data records in available memory space in one of said disk drives”

Corresponding structure: “disk drive manager 102-1 and control unit 101”

“responsive to”: “after and in reaction to”

construction_

This term is subject to 35 U.S.C. § 112, ¶ 6.

Function: “for writing said received stream of data records in available memory space in one of said disk drives”

Structure: “processor 204 programmed to execute the software subroutine that consists of steps 706 to 711 illustrated in Figure 7 and described at col. 16:65 through col. 17:21 of the '855 patent specification”

Sun does not believe the term “responsive to” needs to be construed. However, if the Court decides to construe this term, Sun contends NetApp’s “after and in reaction” construction cannot properly be read to preclude beginning a write operation prior to the receipt of the last data record in the stream of data records._

The parties agree that this term is a means-plus-function limitation governed by 35 U.S.C. § 112, ¶ 6. That paragraph states: “An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” Claim construction of a means-plus-function limitation requires that the court identify the function of the limitation, and ascertain the corresponding structure in the written description that is necessary to perform that function. Altiris, Inc. v. Symantec Corp., 318 F.3d 1363, 1375 (Fed.Cir.2003).

The parties agree that the function is “writing said received stream of data records in available memory space in one of said disk drives,” but dispute whether the corresponding structure includes the entire control unit 101 and disk drive manager 102-1, as NetApp proposes, or only processor 204 programmed to execute steps 706 to 711, illustrated in Figure 7, as Sun contends.

The disputed term appears in claim 1 of the '855 patent:

1. A data storage system, having a plurality of disk drives each having a single set of at least two predefined data storage characteristics, for storing data records for at least one associated data processor, comprising:

a controller, responsive to one of said disk drives having at least one of said at least two data storage characteristics different than a corresponding one of said at least two data storage characteristics of the remaining ones of said plurality of disk drives, for selecting a common disk drive format comprising a set of said data storage characteristics that are emulatable by all of said plurality of disk drives, comprising;

means, responsive to the receipt of a stream of data records from said associated data processor, for writing said received stream of data records in available memory space in one of said disk drives.

'855 patent, col. 21:7-38.

“ ‘Structure disclosed in the specification is “corresponding” structure only if the specification or prosecution history clearly links or associates that structure to the function recited in the claim.’ ” Altins, 318 F.3d at 1375 (quoting B. Braun Med. v. Abbott Labs., 124 F.3d 1419, 1424 (Fed.Cir.1997)). Section 112 paragraph 6 does not “ ‘permit incorporation of structure from the written description beyond that necessary to perform the claimed function.’ ” Asyst Technologies, Inc. v. Empak, Inc., 268 F.3d 1364, 1369-70 (Fed.Cir.2001) (quoting Micro Chem., Inc. v. Great Plains Chem. Co., 194 F.3d 1250, 1257-58 (Fed.Cir.1999)). “Structural features that do not actually perform the recited function do not constitute corresponding structure and thus do not serve as claim limitations.” Id. at 1370 (citing Chiuminatta Concrete Concepts, Inc. v. Cardinal Indus., Inc., 145 F.3d 1303, 1308-09 (Fed.Cir.1998)). By contrast, structure that is “integral to performing the stated function” does constitute corresponding structure. Gemstar-TV Guide Intern., Inc. v. International Trade Com’n, 383 F.3d 1352, 1362 (Fed. Cir.2004).

In the section entitled “Data Write Operations,” the specification details the write operation, identifies the operational steps corresponding to the function of writing the stream of data records to a disk drive, and identifies certain structure as carrying out the steps. The parties agree that steps 706 to 711 are involved in performing the claimed function, as described in the specification:

This scheduling is accomplished by the subroutine that consists of steps 706-711. At step 706, the control unit 101 determines whether the virtual track instance as updated fits into an available open logical cylinder. If it does not fit into an available open logical cylinder, then at step 707 then this presently open logical cylinder must be closed out and written to the physical layer and another logical cylinder selected from the most free logical device or redundancy group in the disk drive array data storage subsystem 100. At step 708, the selection of a free logical cylinder from the most free logical device takes place. This ensures that the data files received from host processor 11 are distributed across the plurality of redundancy groups in the disk drive array data storage subsystem 100 in an even manner to avoid overloading certain redundancy groups while under-loading other redundancy groups. Once a free logical cylinder is available, either being the presently open logical cylinder or a newly selected logical cylinder, then at step 709, the control unit 101 writes the updated virtual track instance into the logical cylinder and at step 710 the new location of the virtual track is placed in the virtual to logical map in order to render it available to the host processors 11-12. At step 711, control returns to the main routine, where at step 712 the control unit 101 cleans up the remaining administrative tasks to complete the write operation and return to an available state at 712 for further read or write operations from host processor 11.

'855 patent, col. 16:65-17:25.

Sun contends that the specification clearly links only the subroutine of steps 706 to 711 to the actual function of writing the data records to the disks. However, the specification includes additional operational steps within the writing function. The control unit 101 performs the set up for a write operation (step 701) and assures that the virtual track containing the data record to be rewritten is located in the cache memory 113 (step 702). The control unit 101 transfers the modified record data received from the host processor into the cache memory 113 (step 704). The specification explains that once the virtual track is updated with the modified data record, “the control unit 101 must schedule this updated virtual track instance to be written onto a redundancy group somewhere in the disk drive array data storage subsystem 100.” '855 patent, col. 16:61-64. The scheduling for writing the data to the disks is accomplished by steps 706 to 711, but the specification identifies steps 701 to 712 as necessary to perform the entire writing function. The plain language of this “Data Write Operation” section of the specification clearly and repeatedly links “the control unit 101” to performing the write operation.

Sun argues, however, that the structure does not include the entire control unit 101 because it has multiple components, other than processor 204 and the associated control software, that are not associated with the function of writing data records, such as channel interface units 201, channel interface control 202, channel data compression circuit 203 and optical device interface 205. '855 patent, col. 7:19-45. Sun contends that the only structure that is clearly linked to the function of writing data records is processor 204-0 of control unit 101, plus the associated software, that together write the data records. Sun relies on the following specification language to demonstrate the role of processor 204-0 in the writing function:

As can be seen from the architecture illustrated in FIG. 2, all data transfers between a host processor 11 and a redundancy group in the disk drive subsets 103 are routed through cache memory 113. Control of cache memory 113 is provided in control unit 101 by processor 204-0. The functions provided by processor 204-0 include initialization of the cache directory and other cache data structures, cache directory searching and management, cache space management, cache performance improvement algorithms as well as other cache control functions. In addition, processor 204-0 creates the redundancy groups from the disk drives in disk drive subsets 103 and maintains records of the status of those devices. Processor 204-0 also causes the redundancy data across the N data-disks in a redundancy group to be generated within cache memory 113 and writes the M segments of redundancy data onto the M redundancy disks in the redundancy group. The functional software in processor 204-0 also manages the mappings from virtual to logical and from logical to physical devices. The tables that describe this mapping are updated, maintained, backed up and occasionally recovered by this functional software on processor 204-0. The free space collection function is also performed by processor 204-0 as well as management and scheduling of the optical fiber backend channels 104. Many of these above functions are well known in the data processing art and are not described in any detail herein.

'855 patent, col. 7:67-8:28 (emphasis added). See Levy Decl. ¶ 32. In support of its argument that the coxresponding structure is limited to processor 204 executing the software associated with steps 706 to 711, Sun relies on Intel Corp. v. VIA Tech., Inc., 319 F.3d 1357, 1365-66 (Fed.Cir.2003), where the Federal Circuit construed the corresponding structure for the functions “to selectively write data” and “determine whether data is able to be written directly” as the “core logic” (a controller chip executing software) modified by a particular software protocol to perform Fast Write. Id. Sun suggests that the writing function here is similar to the writing function in Intel, and that the corresponding structxxre here is similarly limited to processor 204 executing the control software. However, the issue in Intel differed from the one presented here. There, the Federal Circuit held that the patent was not indefinite even though the specification did not disclose circuitry to show how the core logic was modified, but the parties did not dispute whether a more general purpose computer, rather than the processor, constituted the corresponding structure. Id. at 1366.

Other authorities on which Sun relies are no more compelling. In WMS Gaming v. Int'l Game Tech., 184 F.3d 1339, 1348-49 (Fed.Cir.1999), the Federal Circuit held, “In a means-plus-function claim in which the disclosed structure is a computer, or microprocessor, programmed to carry out an algorithm, the disclosed structure is not the general purpose computer, but rather the special purpose computer programmed to perform the disclosed algorithm.” 184 F.3d at 1349 and n. 4. In WMS Gaming the parties stipulated that the patent disclosed “a microprocessor, or computer, to control the operation of the slot machine, including the operation of the machine in the assignment of numbers to reel stop positions.” Id. at 1347. The Federal Circuit noted that it did not find anything in the patent limiting the “means for assigning” to a microprocessor or computer, but declined to decide an issue that the parties did not present. Id. at 1347 n. 2. Similarly, in Tehrani v. Hamilton Med., Inc., 331 F.3d 1355, 1362 (Fed.Cir.2003), the parties did not dispute whether the microprocessor formed part of the structure, but rather precisely which algorithm it was programmed to perform. The Federal Circuit noted, “We agree with the parties that the structure corresponding to the processing function is the disclosed microprocessor that is programmed to perform the disclosed algorithm. The specification teaches that the ‘first means, which preferably comprises a programmable microcomputer, is controlled by a software algorithm to operate upon the input data and provide digital output data representing the amount and optimum frequency of ventilation required for the next breath.’ ... The district court, however, has not determined the precise algorithm that is part of the recited structure.” 331 F.3d at 1362.

While these cases demonstrate that Sun is correct that a processor executing a software routine may in appropriate circumstances be sufficient to identify corresponding structure, Sun’s proposed structure is too narrow for performing the claimed function here because the specification identifies as integral to and clearly links broader structure to the function of writing data records. For example, the control unit performs the subroutine that consists of steps 706 to 711, as well as other operational steps to perform a data write operation. '855 patent, col. 16:65-17:25. Furthermore, the specification describes the integral role of the cache memory 113, which is contained in the control unit, in the data write operation: “all of the data updating is perfonned in the cache memory 113.” '855 patent, col. 16:32-33. Thus, this structure is also integral to the write operation. Sun is correct that the specification describes the control unit 101 as performing other functions, such as reconstruction of data for a failed disk drive and switching a spare disk drive. See '855 patent, col. 5:52-55. However, the fact that the control unit 101 performs these additional control functions does not preclude the control unit 101 from serving as the structure necessary to perform the stated function of writing the stream of data records to a disk drive as the specification states. The specification identifies the control unit 101, not processor 204, with the control software associated with the data write operation, as performing the function of writing data records. See, e.g., id. at 18:64-67 (“Control software in control unit 101 queries all disk drives in the redundancy group to identify the cylinder, track and sector format of all the disk drives in the redundancy group.”).

NetApp contends that disk drive manager 102 is also directly involved in performing the claimed function and therefore part of the corresponding structure, citing the specification:

Thus, the control and drive circuits 121 in disk drive manager 102-1 perform the data and control signal interface and transmission function between the commodity disk drives of disk drive subset 103-1 and control unit 101.

'855 patent, col. 8:63-67. The specification demonstrates that the disk drive manager interconnects disk drives with optical fiber backend channels and includes an input/output circuit that provides a hardware interface to interconnect the optical fiber backend channels with the data paths that serve control and drive circuits. '855 patent, col. 5:61-65.

Whether the disk drive manager 102 (or at least its control and drive circuits 121) is part of the corresponding structure is determined by whether the writing function includes the data and control signal interface and transmission function. See Gemstar-TV Guide Intern., Inc. v. International Trade Com’n, 383 F.3d 1352, 1363 (Fed.Cir.2004). In Gemstar, the parties disputed whether the video switcher was part of the corresponding structure to perform the recited function of “displaying the television schedule on the television screen as a grid,” or whether the corresponding structure comprised only the CPU and video display generator, and the video switcher was merely a conduit for coupling the means for displaying and the television. Id. at 1361. The Federal Circuit determined that the video switcher was “integral to performing the stated function,” reasoning as follows:

the combination of a CPU, video display generator, and video switcher is required to perform the function of displaying the television schedule in a grid format on the television screen. Without the transmission of electrical signals by the video display generator to enable the video switcher, the television schedule would not be selectively displayed on the television screen and would not be displayed in grid format, as are required by the functional statement of the claim limitation.

383 F.3d at 1362.

In Gemstar, the Federal Circuit distinguished Asyst Tech., Inc. v. Empak, Inc., 268 F.3d 1364, 1369-70 (Fed.Cir.2001), on which Sun relies here. In Asyst, the Federal Circuit determined that the functions of receiving and processing digital information recited in claim 1 of the '421 patent were performed by the local control processor, but that the corresponding structure did not include external cables or devices that were connected to the processor, reversing the district court’s holding that the corresponding structure in-eluded the communication line 51 between the processor, or microcomputer means, and the communication means. 268 F.3d at 1370-71. The Federal Circuit noted in Asyst that the specification did not refer to line 51 in the description of the “receiving” and “processing” functions of the processor, and determined that the patent did not clearly link line 51 to the recited functions of claim 1. Id. While communication line 51 “enabled” the microcomputer means to perform the recited functions, it did not actually perform the functions. Id. As Gemstar explained, that construction in Asyst was compelled by the identification of the functions as receiving and processing the data because only the microcomputers performed these functions, not communication wires. 383 F.3d at 1362-63.

By contrast, the Federal Circuit also construed another means-plus-function element in a different claim in Asyst, namely, the “fourth means ... for controlling [the receipt of the transportable containers and the processing of the articles within the containers] and for transmitting information related to the processing performed [to the transportable container].” 268 F.3d at 1372. As to this “fourth means,” the court held that communication line 51 was part of the corresponding structure because line 51 connected the local process controller that performed the first recited function, controlling activities on the workstation, with the communication means that performed the second function, transmitting information to the container. Id. The Federal Circuit concluded that because the means that performed those two functions consisted of the “entire complex comprising the local process controller 20 and the communication means 50[,] ... it also necessarily encompasses structure that connects the two, i.e., communication line 51.” Id. As the court noted, the language of this “fourth means” limitation was “significantly different” from the language of the microcomputer means limitation which the court construed to exclude the communication line 51. Id.

Gemstar and Asyst teach the importance of focusing on the exact function that the structure is performing. NetApp has not demonstrated that the disk drive manager 102 is necessary to accomplish the function of writing data in available memory space in a disk drive. Significantly, the “Data Write Operation” section of the specification never even mentions the disk drive manager 102. By contrast, in Gemstar, the Federal Circuit deemed the video switcher integral to performing the function of displaying the television schedule on a television screen where the written description indicated that the video switcher, in combination with a CPU and video display generator, was required to perform the stated function. 383 F.3d at 1361-62. Here, the disk drive manager 102 is necessary for performing interface and transmission function, '855 patent, col. 8:63-67, but not the writing function itself, which as described in the specification is performed by control unit 101. The disk drive manager 102 connects the disk drives with control unit 101, id., but only control unit 101 actually writes the data records. The data records are written in the disk drives, but the disk drives themselves do not perform the write operation. Unlike the “fourth means” construed in Asyst, which required a structure connecting two discrete components to perform two functions, 268 F.3d at 1372, the writing means claimed in the '855 patent does not assign functions to separate structures that must be linked. The disk drive manager 102 enables the control unit 101 to write data records to the disk drives, but neither the disk drive manager nor the disk drives perform that function. Id. at 1371.

During oral argument, NetApp conceded that there was no dispute that the term “one of said disk drives” did not require that all streams of data records received over time be written to the same disk drive. NetApp also conceded that the dispute over the phrase “responsive to the receipt of a stream of data records from said associative data processor” concerned a separate limitation and was not submitted here for claim construction. The Court further deferred ruling on the parties’ dispute over the term “stream of data records,” which the parties acknowledged was a separately identified term for claim construction.

For the reasons set forth above, the Court construes “means, responsive to the receipt of a stream of data records from said associated data processor, for writing said received stream of data records in available memory space in one of said disk drives” as a means-plus-function limitation, having the function of “writing said received stream of data records in available memory space in one of said disk drives” and the corresponding structure of “control unit 101 programmed to execute the steps 701 through 712 illustrated in Figure 7 and described under the heading ‘Data Write Operation’ at column 16:26 through column 17:25 of the '855 patent specification.”

C. '012 Patent

The '012 patent, “Disk Scrubbing System,” is directed to a data storage subsystem that emulates the format and operation of a large form factor disk drive. The patent addresses the process of “disk scrubbing,” or verifying the integrity of data written to disk drives. What is newly claimed in the '012 patent is identifying and selecting memory locations containing customer or redundancy data and verifying those locations on a priority basis. '012 patent, col. 2:61-67. In the claimed invention, the disk drive array is divided into a plurality of logical partitions, including “dedicated partitions” that are storing data and “free partitions” that are available to store data in the data storage subsystem. The claimed invention determines whether the partitions are dedicated or free. Id. at col. 17:38-63, col. 20:40-62. The parties dispute two claim terms in the '012 patent.

3. “Means responsive to said reading of said memory controller for periodically verifying the integrity of data currently stored in each of said identified dedicated partitions”

Disputed Claim Term: “means responsive to said reading of said memory controller for periodically verifying the integrity of data currently stored in each of said identified dedicated partitions” (Claim 1, '012 patent)_

NetApp’s construction_Sun’s

Periodically verifying the integrity of data currently stored in each of said identified dedicated partitions: “periodically verifying only the integrity of data currently stored in each of said identified partitions”

Responsive to: “after and in reaction to”

Corresponding structure of nested “means” terms:

• “means ... for reading data”: “control unit 101 and disk drive manager 102-1”

• “means ... for generating error check information”: “disk drive subassembly”

• “means ... for detecting errors”: “disk drive subassembly”

• “means ... for correcting said data containing errors”: “control unit 101”

construction_

Sun contends this term is not a means-plus-function limitation.

If the Court concludes this is a means-plus-function limitation, then the function is: “periodically verifying the integrity of data currently stored in each of said identified dedicated partitions.”

Sun contends NetApp’s construction of the functional language incorrectly adds an only limitation and that the term “only” should not be added to the existing claim structure.

If the Court concludes this is a means-plus-function limitation, then the corresponding structure is: “processor 204 of control unit 101 programmed to execute the software processes that read data from selected track (item 1202 of Figure 12), generate CRC for read data (item 1203 of Figure 12), determine whether generated CRC and read CRC match (item 1209 of Figure 12), and reconstruct data of selected track having mismatched CRC (item 1008 of Figure 10).”

While Sun initially disputed whether this term is a means-plus-function limitation, both parties now recognize that it is a means-plus-function nesting term for the four nested means-plus-function limitations. Although the parties did not address this issue in the briefs, the Court may ultimately need to conduct an analysis under 35 U.S.C. § 112, ¶ 6 to determine whether the structures corresponding to each of the nested terms are together sufficient to perform the claimed function of this term. See Rodime PLC v. Seagate Tech., Inc., 174 F.3d 1294, 1303-04 (Fed. Cir.1999).

The parties dispute whether the function is limited to periodically verifying “only” the integrity of data currently stored in each of said identified partitions; construction of the “responsive to” limitation; and the corresponding structure.

The disputed claim terms of the '012 patent appear in claim 1:

1. A data storage subsystem that receives data from at least one connected data processor and stores said data on a plurality of disk drives divided into a plurality of logical partitions, said logical partitions comprising dedicated partitions currently storing data and free partitions available to store data, said data storage subsystem comprising:

a memory controller independent of said plurality of disk drives comprising means for identifying said dedicated and said free partitions;

means for reading said memory controller to determine the identity of said dedicated partitions; and

means responsive to said reading of said memory controller for periodically verifying the integrity of data currently stored in each of said identified dedicated partitions, said means for periodically verifying comprising: means for reading data in each of said identified dedicated partitions;

means responsive to said reading of data from each said identified dedicated partition for generating error check information from said read data;

means responsive to said generation of said error check information for detecting errors in data in each said identified dedicated partition; and means responsive to said detection of errors for correcting said data containing errors.

'012 patent, col. 17:38-63.

NetApp contends that the function requires verifying only the integrity of partitions containing active, or current, data. The language of claim 1 itself distinguishes between “dedicated partitions currently storing data” and “free partitions available to store data.” Claim 1 recites the means-plus-function limitation “for periodically verifying the integrity of data currently stored in each of said identified dedicated partitions.” '012 patent, col. 17:40-43, 50-52 (emphasis added). Turning to the specification, NetApp is correct that the specification refers only to verifying, or scrubbing, the active memory:

This system avoids the data integrity problems of the prior art by periodically verifying the integrity of the data stored on the disk drives of the data storage system. This is accomplished by one or more background processes that cycle through predetermined segments of active memory to verify the integrity of the data stored on the disk drives of the data storage subsystem.

'012 patent, col. 2:18-21.

As Sun points out, claim 1 must be construed broadly enough to permit the practice of dependent claims, including dependent claim 9, which recites a means for verifying administrative data in free partitions:

9. The data storage subsystem of claim 1 further comprising:

means responsive to said reading of said memory controller for periodically verifying the integrity of administrative data stored in each of said identified free partitions, ...

'012 patent, col. 18:63-66. NetApp contends that the doctrine of claim differentiation does not apply here to construe independent claim 1 so broadly because dependent claim 9 does not refine the verifying means recited in independent claim 1, which is focused only on the means for processing dedicated partitions, but rather adds to claim 1 by requiring another means for processing free partitions. NetApp argues that it would not be inconsistent to limit the “means for periodically verifying” in claim 1 to dedicated partitions and allow claim 9 to recite a separate means for processing free partitions. Although NetApp is correct that the “further comprising” language of claim 9 indicates that a means is being added to the data storage subsystem of claim 1, claim 9 is dependent on claim 1, and thereby incorporates by reference all the limitations of that claim. See Monsanto Co. v. Syngenta Seeds, Inc., 503 F.3d 1352, 1357-58 (Fed.Cir.2007) (holding that “further comprising” claim was in dependent form and incorporated the limits of the overarching independent claim), petition for cert, dismissed, 553 U.S. 1077, 129 S.Ct. 394, 171 L.Ed.2d 809 (2008). Thus, NetApp’s proposed “only” limitation would preclude the verifying means from scrubbing the administrative data stored in a free partition, thereby effectively reading claim 9 out of the patent. Claim 1 uses the open term “comprising,” thus allowing for additional structures to be added to the data storage subsystem that the data subsystem of claim 1 does not itself include. Although claim 1 does not claim the function of verifying the administrative data in the free partitions, neither does claim 1 preclude adding that functionality in a dependent claim as in claim 9.

NetApp also relies on the patent prosecution history, in which the applicants distinguished the claimed invention from the prior art by stating that the claimed invention scrubbed only active data. The Court may rely on the prosecution history to inform the meaning of the claim language: “Like the specification, the prosecution history provides evidence of how the PTO and the inventor understood the patent. Furthermore, like the specification, the prosecution history was created by the patentee in attempting to explain and obtain the patent. Yet because the prosecution history represents an ongoing negotiation between the PTO and the applicant, rather than the final product of that negotiation, it often lacks the clarity of the specification and thus is less useful for claim construction purposes.” Phillips v. AWH Corp., 415 F.3d 1303, 1317 (Fed.Cir.2005) (citations omitted). The Federal Circuit has “declined to apply the doctrine of prosecution disclaimer where the alleged disavowal of claim scope is ambiguous.” Omega Eng’g, Inc. v. Raytek Corp., 334 F.3d 1314, 1324 (Fed. Cir.2003). “But where the patentee has unequivocally disavowed a certain meaning to obtain his patent, the doctrine of prosecution disclaimer attaches and narrows the ordinary meaning of the claim congruent with the scope of the surrender.” Id.

To demonstrate that the applicants distinguished the invention over the prior art as verifying only partitions containing active data, NetApp cites the Preliminary Amendment dated March 6, 1996, which was submitted before claims 1 and 9 and the terms “dedicated partitions” and “free partitions” were added to the application: “the claimed invention periodically verifies the integrity of (e.g. scrubs) only logical partitions identified as containing ‘active’ data.” '012 Patent File History, 3/6/96 Amendment at 4 (emphasis in original). The Preliminary Amendment further states, “The prior art therefore teaches away from a fundamental concept of the claimed invention which improves performance of the scrubbing process in a data storage subsystem by scrubbing (periodically verifying the integrity of) only those logical partitions which are identified as containing active data.” Id. at 6 (italicized emphasis added; bolded emphasis in original). NetApp argues that “one of ordinary skill in the art would have understood from the patentees’ statements to the Patent Office that this invention, and specifically this function, requires scrubbing only the dedicated partitions.” Ganger Decl. ¶ 34. While the applicants stated that “the specification at page 29, line 13-24, recites (in discussing figure 10) that free cylinders (those not containing active data) are skipped in the scrub processing,” in the same submission to the PTO they also spelled out a single, limited exception: “Figure 10 so indicates that freed cylinders are not scrubbed (other than the last track thereof which contain administrative data) by the scrub processes of the claimed invention.” 3/6/96 Amendment at 5 (emphasis added). Taken in context, these statements in the Preliminary Amendment demonstrate a clear and unmistakable disavowal of scrubbing free partitions with the sole exception of scrubbing the track containing administrative data.

Further, in the October 1, 1996 Amendment, the applicants reacted to the examiner’s objections and rejection of the claims by “not reciting ‘active