Disk scheduling system with bounded request reordering
AssigneeSun Microsystems, Inc.
InventorMichael A. DeMoney
Life of this patent
Estimating the term…
Abstract
A disk scheduling system with bounded request reordering. Disk access requests may be performed during traversals of a disk head across a disk. Each traversal may have a specified direction of motion. A plurality of disk accesses may be performed during a disk head traversal. The overall number of disk access requests for a given disk head traversal may be limited to a maximum number N. By limiting the number of disk requests for each traversal, a bound may effectively be placed on the amount of time it takes to satisfy any single disk request.
Claims33
A disk storage system comprising:
- a disk for storing data;
- a disk head for reading said data from said disk;
- and
- a scheduler for receiving a plurality of disk access requests, wherein said scheduler is configured to schedule disk access requests to a first traversal of said disk head, and, in response to determining that a total number of N requests have been scheduled to said first traversal, to schedule remaining disk access requests to one or more additional traversals of said disk head.
A method of scheduling disk access requests in a disk storage system, the disk storage system including a disk for storing data and a disk head for reading data, the method comprising:
- scheduling a plurality of disk access requests to a first traversal of said disk head;
- and
- scheduling remaining disk access requests to one or more additional traversals of said disk head in response to determining that a total number of N requests have been scheduled to said first traversal of said disk head.
A disk storage system comprising:
- a disk for storing data;
- a disk head for reading said data from said disk;
- and
- a traversal list including a plurality of entries, wherein each of said entries includes a list of disk requests for a traversal of said disk head, and wherein said list of disk requests may include up to N disk access requests.
A method of scheduling disk access requests in a disk storage system, said disk storage system including a disk head for reading data from a disk, the method comprising:
- maintaining a list of disk access requests scheduled for execution during a traversal of said disk head;
- determining from said list whether a number of disk access requests schedule for a first traversal of said disk head has reached a maximum number (N);
- and
- scheduling said additional disk access requests to additional traversals in response to determining said number of disk requests scheduled for said first traversal has reached said maximum number (N).
Dependencies are inferred from the claim text.