Disk drive for dynamically allocating memory accessed concurrently by a host interface and a disk interface to facilitate large host commands

• US 6,745,283 B1
• Filed: 04/16/2002
• Issued: 06/01/2004
• Est. Priority Date: 04/16/2002
• Status: Expired due to Fees

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Dang, Quoc N.
• Primary Examiner(s): BATAILLE, PIERRE MICHE
• Application Number:
  US10/123,967
• Time in Patent Office: 777 Days
• Field of Search: 711/113, 711/112, 711/114, 711/170, 711/171, 711/172, 707/200, 707/206
• US Class Current: 711/113
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2212/312 In storage controller
• 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 disk drive is disclosed comprising a disk and a semiconductor memory comprising addressable locations for staging and caching data, wherein each addressable location having an allocation status. When a large write command is received from a host to write write-data to the disk, a disk controller dynamically allocates a plurality of the addressable locations relative to the size of the write command and the allocation status of the addressable locations. The write-data received from the host is stored in the dynamically allocated addressable locations while concurrently reading the write-data from the dynamically allocated addressable locations and writing the write-data to the disk. The dynamically allocated addressable locations are re-used for storing write-data received from the host after writing the write-data to the disk.

Claims

1. A disk drive comprising:

(a) a disk;

(b) a head actuated radially over the disk;

(c) a semiconductor memory comprising addressable locations for staging and caching data, wherein each addressable location having an allocation status; and

(d) a disk controller for;

receiving a write command from a host to write write-data to the disk, the write-data comprising a first segment, a second segment and a third segment;

dynamically allocating a plurality of the addressable locations relative to the size of the write command and the allocation status of the addressable locations;

receiving the first segment of write-data from the host and storing the first segment of write-data in the dynamically allocated addressable locations;

receiving the second segment of write-data from the host and storing the second segment of write-data in the dynamically allocated addressable locations while concurrently reading the first segment of write-data from the dynamically allocated addressable locations and writing the first segment of write-data to the disk; and

re-using the dynamically allocated addressable locations for storing the third segment of write-data received from the host after writing the first segment of write-data to the disk.

2. The disk drive as recited in claim 1, wherein:

(a) the addressable locations for staging read-data to facilitate read commands;

(b) the disk controller for;

receiving a read command from the host to read read-data from the disk, the read-data comprising a first segment, a second segment and a third segment;

dynamically allocating a plurality of the addressable locations relative to the size of the read command and the allocation status of the addressable locations;

reading the first segment of read-data from the disk and storing the first segment of read-data in the dynamically allocated addressable locations;

reading the second segment of read-data from the disk and storing the second segment of read-data in the dynamically allocated addressable locations while concurrently reading the first segment of read-data from the dynamically allocated addressable locations and transmitting the first segment of read-data to the host; and

re-using the dynamically allocated addressable locations for storing the third segment of read-data read from the disk after transmitting the first segment of read-data to the host.

3. The disk drive as recited in claim 2, wherein:

(a) the allocation status is assigned a value selected from the group consisting of free, available, valid, and dirty;

(b) the free allocation status indicates an addressable location is not allocated;

(c) the available allocation status indicates an addressable location stores cached write-data written to the disk and therefore available for re-allocation;

(d) the valid allocation status indicates an addressable location stores cached read-data that can be selectively re-allocated; and

(e) the dirty allocation status indicates an addressable location stores staged write-data not yet written to the disk and therefore not available for re-allocation.

4. The disk drive as recited in claim 3, wherein when dynamically allocating the plurality of addressable locations:

(a) the disk controller dynamically allocates addressable locations having a free allocations status first;

(b) the disk controller dynamically allocates addressable locations having an available allocation status second; and

(c) the disk controller dynamically allocates addressable locations having a valid allocation status third.

5. The disk drive as recited in claim 4, wherein before dynamically allocating all of the addressable locations having a valid allocation status, the disk controller writes at least part of the staged write-data to the disk, changes the corresponding addressable locations from a dirty allocation status to an available allocation status, and dynamically allocates the addressable locations updated to the available allocation status.

6. The disk drive as recited in claim 4, wherein when the disk controller dynamically allocates the addressable locations having a valid allocation status, the disk controller selects the addressable locations storing the least recently used cached read-data.

7. The disk drive as recited in claim 3, wherein the number of addressable locations dynamically allocated by the disk controller increases with the number of addressable locations having a free allocation status and an available allocation status.

8. A method of processing host commands in a disk drive, the disk drive comprising a disk, a head actuated radially over the disk, a semiconductor memory comprising addressable locations for staging and caching data, wherein each addressable location having an allocation status, the method comprising the steps of:

(a) receiving a write command from a host to write write-data to the disk, the write command comprising a first segment, a second segment and a third segment;

(b) dynamically allocating a plurality of the addressable locations relative to the size of the write command and the allocation status of the addressable locations;

(c) receiving the first segment of write-data from the host and storing the first segment of write-data in the dynamically allocated addressable locations;

(d) receiving the second segment of write-data from the host and storing the second segment of write-data in the dynamically allocated addressable locations while concurrently reading the first segment of write-data from the dynamically allocated addressable locations and writing the first segment of write-data to the disk; and

(e) re-using the dynamically allocated addressable locations for storing the third segment of write-data received from the host after writing,the first segment of write-data to the disk.

9. The method as recited in claim 8, wherein the addressable locations for staging read-data to facilitate read commands, the method further comprising the steps of:

(a) receiving a read command from the host to read read-data from the disk, the read-data comprising a first segment, a second segment, and a third segment;

(b) dynamically allocating a plurality of the addressable locations relative to the size of the read command and the allocation status of the addressable locations; and

(c) reading the first segment of read-data from the disk and storing the first segment of read-data in the dynamically allocated addressable locations;

(d) reading the second segment of read-data from the disk and storing the second segment of read-data in the dynamically allocated addressable locations while concurrently reading the first segment of read-data from the dynamically allocated addressable locations and transmitting the first segment of read-data to the host; and

(e) re-using the dynamically allocated addressable locations for storing the third segment of read-data read from the disk after transmitting the first segment of read-data to the host.

10. The method as recited in claim 9, wherein:

(a) the allocation status is assigned a value selected from the group consisting of free, available, valid, and dirty;

(b) the free allocation status indicates an addressable location is not allocated;

(c) the available allocation status indicates an addressable location stores cached write-data written to the disk and therefore available for re-allocation;

(d) the valid allocation status indicates an addressable location stores cached read-data that can be selectively re-allocated; and

(e) the dirty allocation status indicates an addressable location stores staged write-data not yet written to the disk and therefore not available for re-allocation.

11. The method as recited in claim 10, wherein when dynamically allocating the plurality of addressable locations:

(a) the addressable locations having a free status are dynamically allocated first;

(b) the addressable locations having an available status are dynamically allocated second; and

(c) the addressable locations having a valid status are dynamically allocated third.

12. The method as recited in claim 11, wherein before dynamically allocating all of the addressable locations having a valid allocation status, at least part of the staged write-data is written to the disk, the corresponding addressable locations are changed from a dirty allocation status to an available allocation status, and the addressable locations updated to the available allocation status are dynamically allocated.

13. The method as recited in claim 11, wherein when allocating addressable locations having a valid allocation status, further comprising the step of selecting the addressable locations storing the least recently used cached read-data.

14. The method as recited in claim 10, wherein the number of addressable locations dynamically allocated increases with the number of addressable locations having a free allocation status and an available allocation status.