Methods and Apparatus for Implementing Virtualization of Storage within a Storage Area Network

• US 20080320134A1
• Filed: 08/27/2008
• Published: 12/25/2008
• Est. Priority Date: 01/23/2002
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Edsall, Thomas James, Gai, Silvano
• Granted Patent: US 8,725,854 B2
• Time in Patent Office: Days
• US Class Current: 709/224
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

Methods and apparatus for implementing storage virtualization on a network device of a storage area network are disclosed. A frame or packet is received at a port of the network device. It is then determined that the frame or packet pertains to access of a virtual storage location of a virtual storage unit representing one or more physical storage locations on one or more physical storage units of the storage area network. A virtual-physical mapping between the one or more physical storage locations and the virtual storage location is then obtained. A new or modified frame or packet is then sent to an initiator or a target specified by the virtual-physical mapping.

Claims

1. A method of implementing storage virtualization on a network device of a storage area network, the method comprising:

(a) receiving a frame or packet at a port of the network device;

(b) determining that the frame or packet pertains to access of a virtual storage location of a virtual storage unit representing one or more physical storage locations on one or more physical storage units of the storage area network, wherein the virtual storage unit comprises a VLUN or other virtual representation of storage on the storage area network;

(c) obtaining a virtual-physical mapping between the one or more physical storage locations and the virtual storage location;

(d) sending a new or modified frame or packet to an initiator or a target specified by the virtual-physical mapping; and

(e) requesting a lock of the one or more physical storage locations by said port of the network device prior to submitting the frame or packet to the one or more physical storage locations.

2. The method as recited in claim 1, wherein the frame or packet is a read or write command.

3. The method as recited in claim 1, wherein requesting the lock of the one or more physical storage locations includes sending a lock request to a single master port of a network device within the storage area network, wherein the master port is adapted for managing lock requests.

4. The method as recited in claim 1, wherein (b), (c), (d) and (e) are performed by logic that is dedicated to only said port of the network device

5. The method as recited in claim 1, wherein (b), (c), (d) and (e) are performed by a dedicated processor that is dedicated to only said port of the network device.

6. The method as recited in claim 1, wherein determining that the frame or packet pertains to access of a virtual storage location comprises identifying an address of the virtual storage unit in the frame or packet from the initiator.

7. The method as recited in claim 6, wherein the address is a destination address.

8. The method as recited in claim 1, wherein determining that the frame or packet pertains to access of a virtual storage location comprises identifying an address of the port in a destination address field of the frame or packet from the target.

9. The method as recited in claim 1, wherein the virtual-physical mapping is defined by a virtualization model.

10. The method as recited in claim 1, the method further comprising:

generating one or more new packets or frames or modifying the received packet or frame in a manner that replaces a destination address of the virtual storage unit with one or more destination addresses of the one or more physical storage units.

11. The method as recited in claim 1, the method further comprising:

generating a new packet or frame or modifying the received packet or frame in a manner that replaces a source address of a physical storage unit with a source address of the virtual storage unit.

12. The method as recited in claim 1, the method further comprising:

generating a new packet or frame or modifying the received packet or frame in a manner that replaces a source address of the initiator with an address of the port on the network device.

13. The method as recited in claim 1, wherein the frame or packet received at a port of the network device comprises a read or write command indicating an amount of memory to be read or written to, the method further comprising:

allocating the amount of memory at the network device.

14. The method as recited in claim 13, further comprising:

receiving a status from the target after the sending of the new or modified frame or packet to the target; and

when the status indicates that the command was successful, de-allocating the amount of memory at the network device.

15. The method as recited in claim 1, wherein the frame or packet received at a port of the network device comprises a read or write command, the method further comprising:

receiving a transfer ready signal from the target after the sending of the new or modified frame or packet, the transfer ready signal indicating that the target is ready to receive a transfer of data.

16. The method as recited in claim 15, further comprising:

sending a transfer ready signal to the initiator after the sending of the new or modified frame or packet, the transfer ready signal indicating that the network device is ready to receive a transfer of data from the initiator;

wherein sending the transfer ready signal to the initiator is performed prior to receiving a transfer ready signal from the target.

17. The method as recited in claim 1, wherein the frame or packet received at a port of the network device comprises a read or write command, the method further comprising:

receiving a status after the sending of the new or modified frame or packet, the status indicating whether the command was successful.

18. The method as recited in claim 17, further comprising:

sending the status to the initiator.

19. The method as recited in claim 17, further comprising:

sending a second new or modified frame or packet to an initiator or a target specified by the virtual-physical mapping;

receiving a second status after the sending of the second new or modified frame or packet, the second status indicating whether the command was successful;

merging the status and the second status; and

sending the merged status to the initiator.

20. The method as recited in claim 17, further comprising:

determining from the status whether the command was successful; and

re-sending the new or modified frame or packet when it is determined that the command was not successful.

21. The method as recited in claim 20, further comprising:

sending the status to the initiator when it is determined that the command was successful.

22. The method as recited in claim 20, wherein the new or modified frame or packet comprises data.

23. The method as recited in claim 20, wherein the new or modified frame or packet comprises a read or write command.

24. The method as recited in claim 20, wherein the frame or packet received at a port of the network device comprises data, the method further comprising:

storing the data in a memory location;

wherein re-sending the new or modified frame or packet comprises;

obtaining the data from the memory location; and

sending a new or modified frame or packet including the obtained data to the initiator or the target specified by the virtual-physical mapping.

25. The method as recited in claim 20, further comprising:

receiving data from the target specified by the virtual-physical mapping; and

storing the data in a memory location.

26. The method as recited in claim 25, wherein re-sending the new or modified frame or packet comprises:

obtaining the data from the memory location; and

sending a new or modified frame or packet including the obtained data to the initiator specified by the virtual-physical mapping.

27. The method as recited in claim 25, wherein re-sending the new or modified frame or packet comprises sending the new or modified frame or packet to an alternate target specified by the virtual-physical mapping, the method further comprising:

receiving alternate data from the alternate target specified by the virtual-physical mapping; and

comparing the alternate data with the data stored in the memory location.

28. The method as recited in claim 27, further comprising:

employing a mirror algorithm to select the alternate target.

29. The method as recited in claim 1, wherein the frame or packet received at the port of the network device comprises a SCSI read command and the new or modified frame or packet sent by the network device comprises a SCSI read command.

30. The method as recited in claim 1, wherein the frame or packet received at the port of the network device comprises a SCSI write command and the new or modified frame or packet sent by the network device comprises a SCSI write command.

31. A network device of a storage area network adapted for implementing storage virtualization, comprising:

(a) means for receiving a frame or packet at a port of the network device;

(b) means for determining that the frame or packet pertains to access of a virtual storage location of a virtual storage unit representing one or more physical storage locations on one or more physical storage units of the storage area network, wherein the virtual storage unit comprises a VLUN or other virtual representation of storage on the storage area network;

(c) means for obtaining a virtual-physical mapping between the one or more physical storage locations and the virtual storage location;

(d) means for sending a new or modified frame or packet to an initiator or a target specified by the virtual-physical mapping; and

(e) means for requesting a lock of the one or more physical storage locations by said port of the network device prior to submitting the frame or packet to the one or more physical storage locations, wherein requesting the lock of the one or more physical storage locations includes sending a lock request to a single master port of a network device within the storage area network, wherein the master port is adapted for managing lock requests.

32. A network device of a storage area network adapted for implementing storage virtualization, comprising:

a processor; and

a memory, at least one of the processor or the memory being adapted for;

(a) receiving a frame or packet at a port of the network device;

(b) determining that the frame or packet pertains to access of a virtual storage location of a virtual storage unit representing one or more physical storage locations on one or more physical storage units of the storage area network, wherein the virtual storage unit comprises a VLUN or other virtual representation of storage on the storage area network;

(c) obtaining a virtual-physical mapping between the one or more physical storage locations and the virtual storage location;

(d) sending a new or modified frame or packet to an initiator or a target specified by the virtual-physical mapping; and

(e) requesting a lock of the one or more physical storage locations by said port of the network device prior to submitting the frame or packet to the one or more physical storage locations, wherein requesting the lock of the one or more physical storage locations includes sending a lock request to a single master port of a network device within the storage area network, wherein the master port is adapted for managing lock requests.

33. The network device as recited in claim 32, wherein the virtual storage unit is a virtual logical unit and the one or more physical storage units are physical logical units.

34. The network device as recited in claim 32, at least one of the processor or the memory being further adapted for:

generating a new packet or frame or modifying the received packet or frame in a manner that replaces a destination address of the port on the network device with a destination address of the virtual storage unit.

35. The network device as recited in claim 32, at least one of the processor or the memory being further adapted for:

receiving a lock grant from the master port of the network device within the storage area network.

36. The network device as recited in claim 35, wherein the granted lock indicates that at least one of exclusive read or write access to the virtual storage location is granted.

37. The network device as recited in claim 35, at least one of the processor or the memory being further adapted for:

sending a transfer ready message to the initiator when the lock grant is received.

38. The network device as recited in claim 35, at least one of the processor or the memory being further adapted for:

requesting a release of the granted lock from the master port of the network device within the storage area network.

39. The network device as recited in claim 38, at least one of the processor or the memory being further adapted for:

receiving a notification that the granted lock has been released by the master port.

40. The network device as recited in claim 38, wherein requesting a release of the granted lock is performed when the read or write command has been successfully completed.

41. The network device as recited in claim 40, wherein the command has been successfully completed when a status indicating that the command was successful is received from the initiator or the target.

42. The network device as recited in claim 32, wherein the frame or packet received at the port of the network device and the new or modified frame or packet sent by the network device are compatible with a standard protocol.

43. The network device as recited in claim 32, wherein the frame or packet received at the port of the network device comprises a read command and the new or modified frame or packet sent by the network device comprises a read command.

44. The network device as recited in claim 32, wherein the frame or packet received at the port of the network device comprises a write command and the new or modified frame or packet sent by the network device comprises a write command.

45. A network device for use in a storage area network supporting virtualization, the network device including a plurality of ports, wherein at least some of said ports comprise

(i) an interface for sending and receiving packets or frames on a storage area network;

and

(ii) logic dedicated to and implemented by said port of the network device, said logic for

identifying frames or packets pertaining to access of a virtual storage location of a virtual storage unit representing one or more physical storage locations on one or more physical storage units of the storage area network, wherein the virtual storage unit comprises a VLUN or other virtual representation of storage on the storage area network;

implementing a virtual-physical mapping between the one or more physical storage locations and the virtual storage location; and

requesting a lock of the one or more physical storage locations by said port of the network device prior to submitting a packet or frame to the one or more physical storage locations, wherein requesting the lock of the one or more physical storage locations includes sending a lock request to a single master port of a network device within the storage area network, wherein the master port is adapted for managing lock requests.

46. A method of implementing storage virtualization on a network device of a storage area network, the method comprising:

(a) receiving a frame or packet at a port of the network device;

(b) obtaining information from the frame or packet pertaining to access of data stored in one or more physical locations on one or more physical storage units of the storage area network, the information identifying one or more of the physical locations or a virtual storage location of a virtual storage unit, the virtual storage location representing the one or more physical storage locations, wherein the virtual storage unit comprises a VLUN or other virtual representation of storage on the storage area network;

(c) obtaining a virtual-physical mapping between the one or more physical storage locations and the virtual storage location;

(d) sending a new or modified frame or packet to an identity specified by the virtual-physical mapping; and

(e) requesting a lock of the one or more physical storage locations by said port of the network device prior to submitting the frame or packet to the one or more physical storage locations.

47. The method as recited in claim 46, wherein (b), (c), (d) and (e) are performed by a dedicated processor that is dedicated to only said port of the network device

48. The method as recited in claim 46, wherein requesting the lock of the one or more physical storage locations includes sending a lock request to a single master port of a network device within the storage area network, wherein the master port is adapted for managing lock requests.