Buffer management system for managing the transfer of data into and out of a buffer in a disc drive

• US 6,330,640 B1
• Filed: 10/26/2000
• Issued: 12/11/2001
• Est. Priority Date: 12/22/1999
• Status: Expired due to Term

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Haines, Jonathan Williams, Cook, Brett Alan, Williams, Steven Scott, Moller, Gregory Paul
• Primary Examiner(s): BRAGDON, REGINALD GLENWOOD
• Application Number:
  US09/696,861
• Time in Patent Office: 411 Days
• Field of Search: 711/112, 710/52, 710/56
• US Class Current: 711/112
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0674 Disk device

Abstract

A method and system for managing the transfer of data into and out of a buffer in a disc drive is disclosed. The operation of the vectored buffer management (VBM) system is administered by a software-based control module. The control module creates and maintains a buffer table by dividing the buffer table into buffer sectors. The buffer sectors are further arranged into buffer segments, or circularly linked lists upon which the buffer table is partitioned. The control module effectuates the transfer by implementing an application module across the buffer table. Once the application module is arbitrarily positioned at an index sector by the control module, data transfer is accomplished when the application module walks through a particular buffer segment identified by the index sector. Specific control of the application module across a buffer segment is administered through host and disc address pointers, which are coupled to host and disc next pointers, respectively.

Claims

1. A buffer management system for managing a transfer of data from a host computer to a recordable disc in a disc drive, the disc drive operating on the host computer, the recordable disc radially divided into a plurality of equal servo segments and circumferentially divided into a plurality of rotational tracks, wherein the disc drive is of a type that data transfers between the host computer and the disc are effectuated by transferring a file defined as a selected number of data blocks to a buffer for temporary storage, the system comprising:

a buffer table divided into a plurality of equal buffer sectors, wherein each one of the plurality of buffer sectors is a sector in a buffer segment defined as one of a plurality of circular linked lists upon which the buffer table is divided;

an application module operable to walk through a particular buffer segment, wherein data is transferred as the buffer segment is walked through; and

a control module to create and maintain the buffer table, the control module being coupled with the application module such that the control module administers the walk through by the application module in response to a next sector instruction in an index sector upon which the application module is currently positioned.

2. The system of claim 1, wherein the application module further comprises:

a host address pointer for committing the data to the buffer, the host address pointer comprising a host next pointer for communicating the next sector instruction of the index sector to the host address pointer, such that the next sector instruction controls positioning of the host address pointer within the particular buffer segment;

a disc address pointer for committing the data from the buffer to the disc, the disc address pointer comprising a disc next pointer for communicating the next sector instruction of the index sector to the disc address pointer, such that the next sector instruction controls the positioning of the disc address pointer within the particular buffer segment.

3. The system of claim 2, wherein the buffer table comprises a free list of sectors readily available to the system for temporary storage, wherein the control module mends the index sector that is to be written to the disc into the free list, such that the index sector becomes available to the system as it is committed to the disc.

4. The system of claim 3, wherein the control module selects the particular buffer segment from the free list in arbitrary fashion, such that the host address pointer is arbitrarily positioned by the control module over a first index sector of the particular buffer segment.

5. The system of claim 3, wherein the sector is mended into the free list of sectors because the data block of the index sector is redundant when compared to the data block of a new command.

6. The system of claim 2, wherein the control module comprises a look-up routine, wherein the look-up routine re-initiates the application module in case the data was committed prematurely.

7. The system of claim 1, wherein the buffer table comprises at least one buffer segment, wherein the buffer table is divided into a maximum number of buffer segments equal to the number of buffer sectors in the buffer table.

8. The system of claim 1, wherein the control module further comprises a merging routine, wherein the merging routine combines a plurality of buffer segments in the buffer table that are to be written onto a plurality of adjacent servo segments, such that the merging routine transforms the plurality of buffer segments into one aggregate buffer segment that can be committed to the disc in one write process.

9. A method for managing a transfer of data from a host computer to a recordable disc in a disc drive, the disc drive operating on the host computer, the recordable disc radially divided into a plurality of equal servo segments and circumferentially divided into a plurality of rotational tracks, wherein the disc drive is of a type that data transfers between the host computer and the disc arc effectuated by transferring a file defined as a selected number of data blocks to a buffer for temporary storage of the file, the method comprising:

(a) maintaining a buffer table divided into a plurality of equal-sized buffer sectors;

(b) arranging each one of the plurality of buffer sectors into at least one buffer segment defined as a circular linked list upon which the buffer table is divided;

(c) selecting a particular buffer segment to temporarily store the file to be transferred from the host computer to the buffer;

(d) transferring the file from the host computer to the buffer by walking through the particular buffer segment in response to a next sector instruction contained in an index sector defined as the buffer sector from which the data is being transferred;

(e) storing the file in the particular buffer segment for a temporary period of time; and

(f) removing the file from the buffer and relocating the file to the recordable disc by walking through the particular buffer segment in response to the next sector instruction contained in the index sector.

10. The method according to claim 9, wherein the maintaining step (a) comprises creating a free list of sectors that is readily available to accept a new data block.

11. The method according to claim 10, wherein the selecting step (c) comprises arbitrarily selecting a first index sector as a beginning to the particular buffer segment that will be used in the storing step (e).

12. The method according to claim 11, wherein the arranging step (b) comprises generating a buffer segment from the free list of sectors by beginning at the arbitrarly selected first index sector and traversing one fewer buffer sector than the selected number of data blocks in the file.

13. The method according to claim 12, wherein the transferring step (d) further comprises:

(i) accepting an incoming data file to be cached; and

(ii) placing the incoming data file into the buffer segment at the index sector.

14. The method according to claim 10 further comprising:

(g) mending the index sector that is to be written to the disc into the free list of sectors such that the index sector becomes available to the system as it is committed to the disc.

15. The method according to claim 14 further comprising:

(h) comparing a data block to be stored in the buffer to each existing data block in each of the buffer segments, such that if the comparing step (h) reveals a redundancy between the existing data block and the data block to be stored in the buffer, the buffer segment which stored the existing data block is mended into the free list.

16. The method according to claim 9, wherein the arranging step (b) comprises organizing the sectors into a plurality of buffer segments up to a maximum number of buffer segments equal to the number of sectors in the buffer table.

17. The method of claim 9 further comprising:

(g) merging together a particular plurality of buffer segments containing data files that are to be written to a plurality of adjacent servo segments, such that a write operation of the particular plurality of buffer segments can be executed in one operation.

18. The method according to claim 9, wherein the transferring step (d) comprises walking through the particular buffer segment with an address pointer coupled to a next pointer, wherein the next pointer communicates the next sector instruction to the address pointer, such that the next sector instruction controls positioning of the address pointer within the particular buffer segment.

19. The method according to claim 9 further comprising:

(g) re-initiating the transferring step (d) and the removing and replacing step (t) in case either one of the steps was performed prematurely.