Finite state machine with a single process context for a RAID system

• US 20020120789A1
• Filed: 02/27/2001
• Published: 08/29/2002
• Est. Priority Date: 02/27/2001
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: RAIDCore, Inc. (Broadcom, Inc.)
• Inventors: Arnott, Randy M., Noya, Eric S., Franklin, Chris R., Wong, Jeffrey T.
• Granted Patent: US 7,219,353 B2
• Time in Patent Office: Days
• US Class Current: 719/325
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G06F 9/4498 Finite state machines

Abstract

A finite state machine (FSM) for a redundant array of independent disk includes a single process context that maintains an entire finite state required for input/output operations performed in a RAID system. The finite state is only updated in response to calls and call-backs. The call-backs can include procedure returns and interrupt signals. The call is received directly from an application program, and the call-backs are received from a driver and passed back directly to the application software by the finite state machine.

Claims

1. A finite state machine for a redundant array of independent disks, comprising:

a single process context configured to maintain an entire finite state required for an input/output operation performed in the redundant array of independent disks;

means for initializing the finite state only in response to a call; and

means for updating the finite state only in response to call-backs.

2. The finite state machine of claim 1 wherein the single process context and the redundant arrays of independent disks operate independently of an operating system process context.

3. The finite state machine of claim 1 the call-backs include procedure returns and interrupt signals.

4. The finite state machine of claim 1 wherein the call is received by the finite state machine directly from application software, and the call-backs are received from a driver and passed back directly to the application software by the finite state machine.

5. The finite state machine of claim 1 wherein the single process context is external to an operating system process context.

6. The finite state machine of claim 1 wherein the input/output operation specifies a multi-block operation.

7. The finite state machine of claim 6 wherein the multi-block operation includes more than two blocks.

8. The finite state machine of claim 7 wherein the finite state machine enters a first state in response to receiving the call, enters a second state in response to a call-back indicating completion an operation on a first block, enters a third state while performing an operation on all but a last block, enters a third state when initiating an operation on the last block, and enters a fourth state upon completing the operation on the last block.

9. The finite state machine of claim 4 wherein the driver is a context-less driver.

10. The finite state machine of claim 8 wherein the context-less driver further comprises:

a software interface configured to translate a driver call into the call for the finite state machine; and

a hardware interface configured to translate the call into a driver calls after the finite state is initialized.

11. The finite state machine of claim 1 further comprising:

a bus connecting the finite state machine to an external computer system via a software interface configured to translate a driver call into the call for the finite state machine; and

a hardware interface configured to translate the call into a driver call after the finite state is initialized.

12. The finite state machine of claim 1 further comprising:

a bus connecting the finite state machine to a context-less driver via a software interface configured to translate a driver call into the call for the finite state machine; and

a hardware interface configured to translate the call into a driver calls after the finite state is initialized.

14. The method of claim 13 wherein the call-backs include procedure returns and interrupt signals.

15. The method of claim 13 wherein the call is received by the finite state machine directly from application software, and the call-backs are received from a driver and passed back directly to the application software by the finite state machine.

16. The method of claim 13 wherein the single process context is external to an operating system process context.

17. The method of claim 13 wherein the input/output operation specifies a multi-block operation.

18. The method of claim 17 wherein the driver is a context-less driver.

19. The method of claim 18 further comprising:

translating, in a software interface, a driver call into the call; and

translating, in a hardware interface, the call into a driver call after the finite state is initialized.

20. The method of claim 1 further comprising:

maintaining a plurality of entire finite states in the single process context, there being one entire finite state for each one of a plurality of concurrent I/O operations performed in the independent arrays of disks.

13. A method for operating a redundant array of independent disks, comprising:

maintaining an entire finite state required for an input/output operation performed in the redundant array of independent disks in a single process context;

initializing the finite state only in response to a call; and

updating the finite state only in response to call-backs.