Method and apparatus for increasing disc drive performance

• US 6,028,725 A
• Filed: 11/04/1997
• Issued: 02/22/2000
• Est. Priority Date: 06/30/1997
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Blumenau, Steven M.
• Primary Examiner(s): KIM, WON TAE C
• Application Number:
  US08/964,442
• Time in Patent Office: 840 Days
• Field of Search: 360/8, 360/48, 369/59, 711/171, 711/173
• US Class Current: 360/8
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0674 Disk device
• CPC Class Codes: G11B 20/00007 Time or data compression or expansion audio compression based on psychoacoustics G10L19/00; data processing for reproducing audio data at different playback speeds G10L21/04; video compression H04N19/00; data compression per se H03M7/30
• CPC Class Codes: G11B 20/1252 for discontinuous data, e.g. digital information signals, computer programme data
• CPC Class Codes: G11B 20/1883 Methods for assignment of alternate areas for defective areas
• CPC Class Codes: G11B 20/1889 with discs
• CPC Class Codes: G11B 2020/1232 sector, i.e. the minimal addressable physical data unit
• CPC Class Codes: G11B 2020/1294 Increase of the access speed
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 2220/2516 Hard disks
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence

Abstract

A method of managing information to be stored on a storage disc in a disc drive system to achieve improved system performance. In one embodiment, data is preferentially stored on the outer tracks of the disc because system performance is greater when accessing outer tracks. Compression techniques may be employed with this embodiment to limit reductions in the storage capacity of the disc. The compression ratio can have any value, including compression ratios less than 2:1, or of F:1, wherein F is a non-integer. In another embodiment, a storage system is provided having sectors of different sizes. The different sized sectors may be on the same disc surface, on different disc surfaces, or on different disc drives. The differently sized sectors can be used to store blocks of information having different sizes to minimize the number of sectors read, thereby improving system performance.

Claims

1. A method of managing information to be stored on at least one disc in a storage system, the at least one disc including a plurality of sectors that are arranged to form a plurality of tracks, the method comprising steps of:

(A) forming a plurality of sector sets from the plurality of sectors, each sector set including Y main sectors and Z corresponding extended sectors;

(B) when a block of information to be written to the at least one disc is compressed by a sufficient amount to be stored within the Y main sectors of one of the plurality of sector sets, storing the block of information in a compressed state in the Y main sectors of the one of the plurality of sector sets and identifying the Z extended sectors of the one of the plurality of sector sets as being in an empty state; and

(C) when a block of information to be written to the at least one disc is not compressed by a sufficient amount to be stored within the Y main sectors of any of the plurality of sector sets, storing the block of information in an uncompressed state partially in the Y main sectors and partially in the Z extended sectors of one of the plurality of sector sets.

2. The method of claim 1, wherein the storage system operates upon blocks of information having an uncompressed block size when in the uncompressed state;

and

wherein step (A) includes a step of forming the plurality of sector sets so that each of the main and extended sectors has a size that is substantially equal to the uncompressed block size divided by X, wherein X equals Y plus Z.

3. The method of claim 2, wherein:

step (B) includes a step of determining that the block of information to be written to the at least one disc is compressed by the sufficient amount to be stored in the Y main sectors of one of the plurality of sector sets when the block is compressed by a compression ratio equal to at least X;

Y; and

step (C) includes a step of determining that the block of information to be written to the at least one disc is not compressed by the sufficient amount when the block is not compressed by a compression ratio equal to at least X;

Y.

4. The method of claim 3, wherein step (A) includes a step of forming the plurality of sector sets so that when the compression ration of X:

Y is reduced to F;

1, F is a non-integer having a fractional component.

5. The method of claim 3, wherein step (A) includes a step of forming the plurality of sector sets so that the compression ration of X:

Y is less than 2;

1.

6. The method of claim 3, wherein step (A) includes a step of forming the plurality of sector sets so that Y is greater than Z.

7. The method of claim 3, wherein step (A) includes a step of forming the plurality of sector sets so that Y is one.

8. The method of claim 3, wherein the at least one disc includes a plurality of discs that each includes at least one surface on which information can be stored, and wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors for each sector set are stored on a different disc surface than their corresponding Z extended sectors.

9. The method of claim 3, wherein step (A) further includes a step of forming the plurality of sector sets so that:

each of the Y main sectors and their corresponding Z extended sectors are formed on a common surface of the at least one disc;

each of the Y main sectors is formed on an outer region of the common surface, the outer region including a first group of the plurality of tracks; and

each of the Z extended sectors is formed on an inner region of the common surface, the inner region including a second group of the plurality of tracks.

10. The method of claim 9, wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors and the Z extended sectors for each of the plurality of sector sets are rotationally offset such that a line passing through a center of the disc and any of the Y main sectors does not pass through any of their corresponding Z extended sectors.

11. The method of claim 10, wherein the storage system includes a disc drive system having a head that accesses information on the at least one disc, and wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors and the Z extended sectors for each of the plurality of sector sets are rotationally offset by an amount that is dependent upon a rate of disc rotation and head seek for the disc drive system, such that a time period for rotation of the at least one disc to move from a first rotational position wherein the Y main sectors are in line with the head to a second rotational position wherein the Z extended sectors are in line with the head is substantially equal to a time period for the head to complete a seek from the Y main sectors to the Z extended sectors.

12. The method of claim 3, wherein:

step (B) includes a step of writing information to the Y main sectors of the one of the plurality of sector sets indicating that the Y main sectors store a block of information in the compressed state; and

step (C) includes a step of writing information to the Y main sectors of the one of the plurality of sector sets indicating that the Y main sectors store a portion of a block of information in the uncompressed state.

13. The method of claim 3, wherein step (A) includes a step of forming each of the plurality of sector sets so that a location on the at least one disc for the Z extended sectors is predetermined by a location on the at least one disc of their corresponding Y main sectors.

14. The method of claim 3, wherein step (A) includes a step of forming the plurality of sector sets so that each includes exactly Z extended sectors.

15. The method of claim 3, wherein the storage system includes a plurality of disc drives, and wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors for each sector set are stored on a different disc drive than their corresponding Z extended sectors.

16. The method of claim 1, wherein Y and Z each is equal to one, and wherein within each of the plurality of sector sets, the main sectors are of a different size than the extended sectors.

17. The method of claim 16, wherein the storage system operates upon blocks of information having an uncompressed block size when in the uncompressed state;

and

wherein step (A) includes a step of forming the plurality of sector sets so that each of the main sectors has a size that is substantially equal to the uncompressed block size multiplied by Y/X, wherein X equals Y plus Z.

18. The method of claim 17, wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors for each sector set are stored on a same disc surface as their corresponding Z extended sectors.

19. The method of claim 16, wherein the at least one disc includes a plurality of discs that each includes at least one surface on which information can be stored, and wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors for each sector set are stored on a different disc surface than their corresponding Z extended sectors.

20. The method of claim 16, wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors for each sector set are stored on a same disc surface as their corresponding Z extended sectors.

21. The method of claim 16, wherein step (A) includes a step of forming each of the plurality of sector sets so that a location on the at least one disc for the Z extended sectors is predetermined by a location on the at least one disc of their corresponding Y main sectors.

22. The method of claim 16, wherein the storage system includes a plurality of disc drives, and wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors for each sector set are stored on a different disc drive than their corresponding Z extended sectors.

23. A storage system, comprising:

at least one disc including a plurality of sectors that are arranged to form a plurality of tracks; and

a controller that manages writing of blocks of information to the at least one disc, the controller being adapted to arrange the plurality of sectors in a plurality of sector sets, each sector set including Y main sectors and Z corresponding extended sectors, the controller being further adapted to manage the writing of blocks of information to the at least one disc so that;

when a block of information to be written to the at least one disc is compressed by a sufficient amount to be stored within the Y main sectors of one of the plurality of sector sets, the controller stores the block of information in a compressed state in the Y main sectors of the one of the plurality of sector sets and identifies the Z extended sectors of the one of the plurality of sector sets as being in an empty state; and

when a block of information to be written to the at least one disc is not compressed by a sufficient amount to be stored within the Y main sectors of any of the plurality of sector sets, the controller stores the block of information in an uncompressed state partially in the Y main sectors and partially in the Z extended sectors of one of the plurality of sector sets.

24. The storage system of claim 23, wherein the storage system operates upon blocks of information having an uncompressed block size when in the uncompressed state;

and

wherein the controller forms the plurality of sector sets go that each of the main and extended sectors has a size that is substantially equal to the uncompressed block size divided by X, wherein X equals Y plus Z.

25. The storage system of claim 24, wherein:

the controller determines that the block of information to be written to the at least one disc is compressed by the sufficient amount to be stored in the Y main sectors of one of the plurality of sector sets when the block is compressed by a compression ratio equal to at least X;

Y.

26. The storage system of claim 25, wherein the controller forms the plurality of sector sets so that when the compression ration of X:

Y is reduced to F;

1, F is a non-integer having a fractional component.

27. The storage system of claim 25, wherein the controller forms the plurality of sector sets so that the compression ration of X:

Y is less than 2;

1.

28. The storage system of claim 25, wherein the controller forms the plurality of sector sets so that Y is greater than Z.

29. The storage system of claim 25, wherein the controller forms the plurality of sector sets so that Y is one.

30. The storage system of claim 25, wherein the at least one disc includes a plurality of discs that each includes at least one surface on which information can be stored, and wherein the controller forms the plurality of sector sets so that the Y main sectors for each sector set are stored on a different disc surface than their corresponding Z extended sectors.

31. The storage system of claim 25, wherein the controller forms the plurality of sector sets so that:

each of the Y main sectors and their corresponding Z extended sectors are formed on a common surface of the at least one disc;

each of the Y main sectors is formed on an outer region of the common surface, the outer region including a first group of the plurality of tracks; and

each of the Z extended sectors is formed on an inner region of the common surface, the inner region including a second group of the plurality of tracks.

32. The storage system of claim 31, wherein the controller forms the plurality of sector sets so that the Y main sectors and the Z extended sectors for each of the plurality of sector sets are rotationally offset such that a line passing through a center of the disc and any of the Y main sectors does not pass through any of their corresponding Z extended sectors.

33. The storage system of claim 25, wherein the controller writes information to the Y main sectors of the one of the plurality of sector sets indicating whether the Y main sectors store a block of information in the compressed state.

34. The storage system of claim 25, wherein the controller forms each of the plurality of sector sets so that a location on the at least one disc for the Z extended sectors is predetermined by a location on the at least one disc of their corresponding Y main sectors.

35. The storage system of claim 25, wherein the storage system includes a plurality of disc drives, and wherein the controller forms the plurality of sector sets so that the Y main sectors for each sector set are stored on a different disc drive than their corresponding Z extended sectors.

36. The storage system of claim 24, wherein Y and Z each is equal to one, and wherein within each of the plurality of sector sets, the main sectors are of a different size than the extended sectors.

37. The storage system of claim 36, wherein the storage system operates upon blocks of information having an uncompressed block size when in the uncompressed state;

and

wherein the controller forms the plurality of sector sets so that each of the main sectors has a size that is substantially equal to the uncompressed block size multiplied by Y/X, wherein X equals Y plus Z.

38. The storage system of claim 37, wherein the controller forms the plurality of sector sets so that the Y main sectors for each sector set are stored on a same disc surface as their corresponding Z extended sectors.

39. The storage system of claim 36, wherein the at least one disc includes a plurality of discs that each includes at least one surface on which information can be stored, and wherein step (A) includes a step of forming the plurality of sector sets so that the Y main sectors for each sector set are stored on a different disc surface than their corresponding Z extended sectors.

40. The storage system of claim 39, wherein the storage system includes a plurality of disc drives, and wherein the controller forms the plurality of sector sets so that the Y main sectors for each sector set are stored on a different disc drive than their corresponding Z extended sectors.

41. The storage system of claim 36, wherein the controller forms the plurality of sector sets so that the Y main sectors for each sector set are stored on a same disc surface as their corresponding Z extended sectors.

42. The storage system of claim 36, wherein the controller forms each of the plurality of sector sets so that a location on the at least one disc for the Z extended sectors is predetermined by a location on the at least one disc of their corresponding Y main sectors.

43. The storage system of claim 36, wherein the controller writes information to the Y main sectors of the one of the plurality of sector sets indicating whether the Y main sectors store a block of information in the compressed state.