Online restriping technique for distributed network based virtualization

• US 7,877,545 B2
• Filed: 09/08/2008
• Issued: 01/25/2011
• Est. Priority Date: 06/06/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Kumar, Sanjaya, Dutt, Dinesh, Mahajan, Umesh, Sharma, Samar, Edsall, Thomas J.
• Primary Examiner(s): Elmore; Stephen C
• Application Number:
  US12/206,475
• Publication Number:
  US 20090006746A1
• Time in Patent Office: 869 Days
• Field of Search: 711/114, 711/150, 711/165, 711/170, 714/7
• US Class Current: 711/114
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

A technique is provided for implementing online restriping of a volume in a storage area network. A first instance of the volume is instantiated at a first port of the fibre channel fabric for enabling I/O operations to be performed at the volume. While restriping operations are being performed at the volume, the first port is able to concurrently perform I/O operations at the volume.

Claims

1. A method of implementing online restriping of a volume in a storage area network, the storage area network including a fibre channel fabric comprised of a plurality of switches which are operable to communicate using a Fibre Channel protocol, the fibre channel fabric including a plurality of ports, the method comprising:

instantiating, by a first port of a first switch of the fibre channel fabric, a first instance of the volume for enabling I/O operations to be performed at the volume;

performing restriping operations at the volume; and

enabling the first port to perform I/O operations at the volume using the first instance of the volume concurrently while at least a portion of the restriping operations are being performed at the volume.

2. The method of claim 1:

wherein the instantiating of the first instance of the volume is implemented by the first port.

3. The method of claim 1:

wherein the first instance of the volume is instantiated by the first switch of the fibre channel fabric.

4. The method of claim 1 further comprising:

instantiating, by a second port of a second switch of the fibre channel fabric, a second instance of the volume for enabling I/O operations to be performed at the volume, wherein the instantiating of the second instance of the first volume is implemented by the second port; and

enabling the second port to perform I/O operations at the volume using the second instance of the volume concurrently while at least a portion of the restriping operations are being performed at the volume, and concurrently while the first port is performing I/O operations at the volume.

5. The method of claim 1 wherein the restriping operations include changing a number of columns of the volume.

6. The method of claim 1 where in the restriping operations include changing a stripe unit size of the volume.

7. The method of claim 1 wherein the restriping operations include changing a stripe unit size of the volume, the method further comprising:

generating a new volume mapping based at least in part upon a desired value of a new stripe unit size of the volume;

selecting a first active region for performing a first portion of restriping operations, wherein a size of the first active region is B bytes;

copying at data from the first active region to a temporary storage location; and

copying the data from the temporary storage location to the first active region using the new volume mapping.

8. The method of claim 1 further comprising:

selecting a first active region of the volume for executing a first portion of restriping operations;

locking of the first active region during execution of the first portion of restriping operations, wherein the locking of the first active region includes denying read/write access to the first active region.

9. The method of claim 1 further comprising:

receiving a first request for accessing a first location of the volume;

determining that the first location corresponds to an ACTIVE region of the volume where a first portion of restriping operations are being performed; and

delaying processing of the first request until it has been determined that the first portion of the restriping operations has been completed.

10. A system of implementing online restriping of a volume in a storage area network, the storage area network including a fibre channel fabric comprised of a plurality of switches which are operable to communicate using a Fibre Channel protocol, the fibre channel fabric including a plurality of ports, the system comprising:

at least one processor;

at least one interface operable to provide a communication link to at least one other network device in the storage area network; and

memory;

the system being operable to;

instantiate, by a first port of a first switch of the fibre channel fabric, a first instance of the volume for enabling I/O operations to be performed at the volume, wherein the instantiating of the first instance of the first volume is implemented by the first port;

perform restriping operations at the volume; and

enable the first port to perform I/O operations at the volume using the first instance of the volume concurrently while at least a portion of the restriping operations are being performed at the volume.

11. The system of claim 10 being further operable to:

instantiate, by a second port of a second switch of the fibre channel fabric, a second instance of the volume for enabling I/O operations to be performed at the volume, wherein the instantiating of the second instance of the volume is implemented by the second port; and

enable the second port to perform I/O operations to be performed at the volume using the second instance of the volume concurrently while at least a portion of the restriping operations are being performed at the volume, and concurrently while the first port is performing I/O operations at the volume.

12. The system of claim 10 wherein the restriping operations include changing a number of columns of the volume.

13. The system of claim 10 where in the restriping operations include changing a stripe unit size of the volume.

14. The system of claim 10 where in the restriping operations include changing a stripe unit size of the volume, the system being further operable to:

generate a new volume mapping based at least in part upon a desired value of a new stripe unit size of the volume;

select a first active region for performing a first portion of restriping operations, wherein a size of the first active region is B bytes;

copy at data from the first active region to a temporary storage location; and

copy the data from the temporary storage location to the first active region using the new volume mapping.

15. The system of claim 10 being further operable to:

select a first active region of the volume for executing a first portion of restriping operations;

lock of the first active region during execution of the first portion of restriping operations, wherein the locking of the first active region includes denying read/write access to the first active region.

16. The system of claim 10 being further operable to:

receive a first request for accessing a first location of the volume;

determine that the first location corresponds to an ACTIVE region of the volume where a first portion of restriping operations are being performed; and

delay processing of the first request until it has been determined that the first portion of the restriping operations has been completed.

17. A switch of a fibre channel fabric in a storage area network, the switch comprising:

a first port;

at least one processor;

at least one interface operable to provide a communication link to at least one other network device in the storage area network; and

memory;

the switch being operable to;

instantiate, at the first port, a first instance of the volume for enabling I/O operations to be performed at the volume;

perform restriping operations at the volume; and

enable I/O operations to be performed at the volume using the first instance of the volume concurrently while at least a portion of the restriping operations are being performed at the volume.

18. The switch of claim 17 wherein the instantiating of the first instance of the volume is implemented by the first port.

19. The switch of claim 17 further comprising:

a second port;

the switch being further operable to;

instantiate, at the second port, a second instance of the first volume for enabling second I/O operations to be performed at the volume, wherein the instantiating of the second instance of the volume is implemented by the second port; and

enable the second port to perform the second I/O operations at the volume using the second instance of the volume concurrently while the first restriping operations are being performed, and concurrently while the first port is performing first I/O operations at the volume;

wherein the first I/O operations are performed independently of the second I/O operations.

20. The switch of claim 17 being further configured or designed to:

enable I/O operations to be performed at the volume without serializing access to the volume.

21. The switch of claim 17 being further operable to implement a first plurality of restriping operations relating to changing of a stripe unit size of the volume, the first plurality of restriping operations comprising:

generating a new volume mapping based at least in part upon a desired value of a new stripe unit size of the volume;

selecting a first active region for performing a first portion of restriping operations, wherein a size of the first active region is B bytes;

copying data from the first active region to a temporary storage location; and

copying data from the temporary storage location to the first active region using the new volume mapping.

22. The switch of claim 17 being further operable to:

select a first active region of the volume for executing a first portion of restriping operations;

lock of the first active region during execution of the first portion of restriping operations, wherein the locking of the first active region includes denying read/write access to the first active region.

23. The switch of claim 17 being further operable to:

receive a first request for accessing a first location of the volume;

determine that the first location corresponds to an ACTIVE region of the volume where a first portion of restriping operations are being performed; and

delay processing of the first request until it has been determined that the first portion of the restriping operations has been completed.

24. A system of implementing online restriping of a volume in a storage area network, the storage area network including a fibre channel fabric comprised of a plurality of switches which are operable to communicate using a Fibre Channel protocol, the fibre channel fabric including a plurality of ports, the system comprising:

means for instantiating, by a first port of a first switch of the fibre channel fabric, a first instance of the volume for enabling I/O operations to be performed at the volume;

means for performing restriping operations at the volume;

means for enabling the first port to perform I/O operations at the volume using the first instance of the volume concurrently while at least a portion of the restriping operations are being performed at the volume;

means for instantiating, by a second port of a second switch of the fibre channel fabric, a second instance of the volume for enabling I/O operations to be performed at the volume, wherein the instantiating of the second instance of the first volume is implemented by the second port; and

means for enabling the second port to perform I/O operations to be performed at the volume using the second instance of the volume concurrently while at least a portion of the restriping operations are being performed at the volume, and concurrently while the first port is performing I/O operations at the volume.