Accelerating internet small computer system interface (iSCSI) proxy input/output (I/O)

• US 8,892,789 B2
• Filed: 12/19/2008
• Issued: 11/18/2014
• Est. Priority Date: 12/19/2008
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Spry, Andrew J.
• Primary Examiner(s): Tsai, Henry
• Assistant Examiner(s): BARTELS, CHRISTOPHER A.
• Application Number:
  US12/317,151
• Publication Number:
  US 20100161843A1
• Time in Patent Office: 2,160 Days
• Field of Search: None
• US Class Current: 710/33
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

The present invention is a method for accelerating proxy Input/Output (proxy I/O). The method includes the step of receiving a command at a primary target storage system. The primary target storage system may be part of a clustered storage array. The command may be a command which was transmitted by an initiator system via a storage area network, and may include a request for data. The method further includes the step of forwarding the command to a session layer of the primary target storage system. Further, when a virtualization layer of the primary target storage system determines that a portion of the data requested in the data request is not stored by the primary target storage system, but is stored by a proxy target storage system included in the plurality of storage systems, the method further includes providing a proxyIO request to a proxy initiator of the primary target storage system. Further, the method may further include, based on the proxyIO request, generating a proxyDataIn request and providing the proxyDataIn request to an I/O controller for the primary target storage system.

Claims

1. A method for accelerating proxy Input/Output (proxy I/O), comprising:

receiving a command at a primary target storage system included in a plurality of storage systems of a target-based block storage cluster, the primary target storage system comprising a CPU, a first I/O controller communicatively coupled to an initiator system, and a second I/O controller communicatively coupled to a proxy target storage system, the command being transmitted by the initiator system to the primary target storage system via a storage area network, the command including a request for data;

forwarding the command to a session layer of the primary target storage system;

when a virtualization layer of the primary target storage system determines that a portion of the data requested in the data request is not stored by the primary target storage system, but is stored by the proxy target storage system included in the plurality of storage systems, the proxy target storage system comprising a CPU and an I/O controller for the proxy target storage system, providing a proxyIO request to a proxy initiator of the primary target storage system;

based on the proxyIO request, generating a proxyDataIn request and providing the proxyDataIn request from the session layer of the primary target storage system to the second I/O controller;

based on the proxyDataIn request, creating a command context via the second I/O controller, said command context being indexed by proxy task ID;

requesting said portion of the data from the proxy target storage system; and

providing, to the initiator system, a received response to the requesting, wherein the providing includes routing the response from the second I/O controller to the first I/O controller by a connection layer command.

2. A method as claimed in claim 1 wherein the requesting of said portion of the data includes:

creating a Small Computer Systems Interface (SCSI) command via the second I/O controller, said SCSI command including a proxy SCSI request for said portion of the data.

3. A method as claimed in claim 2 wherein the requesting of said portion of the data further includes:

transmitting the SCSI command from the second I/O controller to the proxy target storage system.

4. A method as claimed in claim 3 wherein the requesting of said portion of the data further includes:

receiving the SCSI command at the proxy target storage system and forwarding said SCSI command to a SCSI layer of the proxy target storage system.

5. A method as claimed in claim 4, further comprising:

retrieving the received response including said portion of the data requested in the proxy SCSI request of the SCSI command.

6. A method as claimed in claim 5, further comprising:

providing a list of buffers containing said portion of the requested data via the SCSI layer of the proxy target storage system.

7. A method as claimed in claim 6, further comprising:

providing a sendDataIn operation from the SCSI layer of the proxy target storage system to an interne SCSI (iSCSI) layer of the proxy target storage system.

8. A method as claimed in claim 7, further comprising:

providing a dataIn operation from an iSCSI session layer of the proxy target storage system to a connection layer of the second I/O controller said dataIn operation including the list of buffers.

9. A method as claimed in claim 8, further comprising:

generating an iSCSI Data-In Protocol Distribution Unit (iSCSI Data-In PDU) via the I/O controller for the proxy target storage system.

10. A method as claimed in claim 9, further comprising:

transmitting the iSCSI Data-In PDU from the proxy target storage system to the proxy initiator of the primary target storage system, the iSCSI Data-In PDU including said portion of the requested data.

11. A method as claimed in claim 10, further comprising:

setting an Logical Unit Number (LUN) value and a task ID value included in the iSCSI Data-In PDU to same values as an LUN and a task ID included in the initiator system command.

12. A method as claimed in claim 11, further comprising:

supplying iSCSI sequence numbers to the iSCSI Data-In PDU, said sequence numbers associated with a primary session.

13. A method as claimed in claim 12, further comprising:

routing the iSCSI Data-In PDU to a connection of the primary session at the connection layer.

14. A method as claimed in claim 13, further comprising:

transmitting the iSCSI Data-In PDU to the initiator system.

15. A method as claimed in claim 14, further comprising:

providing a dataInComplete event from the I/O controller for the proxy target storage system to the iSCSI layer of the proxy target storage system.

16. A method as claimed in claim 15, further comprising:

providing a sendDataInComplete event from the iSCSI layer of the proxy target storage system to the SCSI layer of the proxy target storage system;

sending a SCSI command completed event and status information from the SCSI layer of the proxy target storage system to the iSCSI layer of the proxy target storage system; and

when a SCSI command status is not sent with the iSCSI Data-In PDU, providing an SCSI Command Response type iSCSI PDU to the proxy initiator of the primary target storage system.

17. A method as claimed in claim 16, further comprising:

when the SCSI Command Response type iSCSI PDU is received by the primary target storage system from the proxy target storage system, sending a proxyDataInComplete event from the second I/O controller to an iSCSI session layer of the proxy initiator, the proxyDataInComplete event including a proxy I/O data transfer status;

sending a proxyIOComplete event to the primary target storage system; and

providing a SCSI Response type iSCSI PDU to the initiator system.

20. The method of claim 1, wherein the requesting of said portion of the data includes:

receiving an iSCSI Data-In Protocol Distribution Unit (PDU) received from the proxy target storage system in response to the proxyIO request; and

routing the iSCSI Data-In PDU from the second I/O controller of the primary target storage system communicatively coupled to the proxy target storage system to the first I/O controller of the primary target storage system communicatively coupled to the initiator system, wherein the routing is performed entirely at the connection layer.

18. A non-transitory computer-readable medium having computer-executable instructions for performing a method for accelerating proxy Input/Output (proxy I/O), said method comprising:

receiving a command at a primary target storage system included in a plurality of storage systems of a target-based block storage cluster, the primary target storage system comprising a CPU, a first I/O controller communicatively coupled to an initiator system, and a second I/O controller communicatively coupled to a proxy target storage system, the command being transmitted by the initiator system to the primary target storage system via a storage area network, the command including a request for data;

forwarding the command to a session layer of the primary target storage system;

when a virtualization layer of the primary target storage system determines that a portion of the data requested in the data request is not stored by the primary target storage system, but is stored by the proxy target storage system included in the plurality of storage systems, the proxy target storage system comprising a CPU and an I/O controller for the proxy target storage system, providing a proxyIO request to a proxy initiator of the primary target storage system;

based on the proxyIO request, generating a proxyDataIn request and providing the proxyDataIn request from the session layer of the primary target storage system to the second I/O controller;

based on the proxyDataIn request, creating a command context via the second I/O controller, said command context being indexed by proxy task ID;

requesting said portion of the data from the proxy target storage system; and

providing, to the initiator system, a received response to the requesting, wherein the providing includes routing the response from the second I/O controller to the first I/O controller by a connection layer command.

19. A storage system of a target-based block storage cluster communicatively coupled to an initiator system and to a target storage system, the storage system comprising:

a first input/output (I/O) controller communicatively coupled to the initiator system via a storage area network and operable to communicate with the initiator using at least an iSCSI protocol;

a first processor associated with the first I/O controller;

a second input/output (I/O) controller communicatively coupled to the target storage system and operable to communicate with the target storage system using at least an iSCSI protocol; and

a second processor associated with the second I/O controller,

wherein the storage system is operable to, upon determining that a first request received from the initiator system involves data stored by the target storage system;

provide, to the second I/O controller, information identifying a session between the initiator system and the first I/O controller;

create, by the second I/O controller, a second request for the data stored by the target storage system;

create, by the second I/O controller, a command context relating the second request to the session; and

forward a response to the second request received from the target storage system to the initiator system by modifying the response according to the command context, providing the modified response from the second I/O controller to the first I/O controller via a connection layer command, and providing the modified response from the first I/O controller to the initiator system via the session.