Protocol translation in a storage system
A storage switch in accordance with an embodiment of the invention is a highly scalable switch that allows the creation of a SAN that is easy to deploy and that can be centrally managed. Moreover, such a storage switch also allows the deployment of a global infrastructure, allowing the resources of the SAN, such as storage devices, to essentially be positioned anywhere on the globe. Further, such a storage switch allows a multi-protocol SAN, e.g., one that includes both iSCSI or Fibre Channel, and processes data packets at “wire speed.” To further enable wire-speed processing, a switch in accordance with the invention has “intelligence” distributed to each of its linecards, through which it classifies packets into data and control packets, it performs virtualization functions, and it performs protocol translation functions. A switch in accordance with the invention further performs serverless storage services such as mirroring, snapshot, and replication.
1. A method for use in a system for storing and accessing data, the method comprising:
(a) receiving a first packet formatted in accordance with a first protocol from a first device that operates in accordance with the first protocol;
(b) translating the first packet to a second packet formatted in accordance with a second protocol, wherein said translating includes mapping at least some of the fields of the first packet formatted in accordance with the first protocol into the second packet formatted in accordance with the second protocol;
(c) forwarding the second packet to a second device that operates in accordance with the second protocol; and
wherein said translating occurs without buffering the packet.
2. The method of claim 1 , wherein said translating occurs at wire speed.
3. The method of claim 1 , wherein translating further includes adding information into any fields of the second packet formatted in accordance with the second protocol that are not mapped from the first packet formatted in accordance with the first protocol.
4. The method of claim 1 , wherein the first protocol is iSCSI and the second protocol is Fibre Channel.
5. The method of claim 4 , wherein the first protocol is iSCSI embedded in TCP.
6. The method of claim 1 , wherein the first protocol is Fibre Channel and the second protocol is iSCSI.
7. The method of claim 6 , wherein the second protocol is iSCSI embedded in TCP.
8. The method of claim 1 , wherein the first device is an initiator and the second device is a target.
9. The method of claim 1 , wherein the first device is a target and the second device is an initiator.
10. A method for use in a system for storing and accessing data, the method comprising:
receiving a packet formatted in accordance with a first recognized protocol; and
mapping the fields of the packet to a new packet formatted in accordance with a second protocol without buffering the packet.
11. The method of claim 10 , wherein the steps of receiving and mapping are performed at wire speed.
12. The method of claim 10 , wherein mapping includes mapping by a processor the fields of the packet to a new packet formatted in accordance with a second protocol without buffering.
13. The method of claim 10 , wherein the first protocol is iSCSI and the second protocol is Fibre Channel.
14. The method of claim 13 , wherein the first protocol is iSCSI embedded in TCP.
15. The method of claim 10 , wherein the first protocol is Fibre Channel and the second protocol is iSCSI.
16. The method of claim 15 , wherein the second protocol is iSCSI embedded in TCP.
17. The method of claim 10 , wherein the packet contains a SCSI command descriptor block (CDB).
18. A method for use in a system for storing and accessing data, the method comprising:
receiving a packet from a first device, the packet formatted in accordance with one of the iSCSI or Fibre Channel protocols;
if the packet is formatted in accordance with the iSCSI protocol, translating the packet into a Fibre Channel packet by mapping at least some of the fields from the packet formatted in accordance with the iSCSI protocol into the Fibre Channel packet;
if the packet is formatted in accordance with the Fibre Channel protocol, translating the packet into an iSCSI packet by mapping at least some of the fields from the packet formatted in accordance with the Fibre Channel protocol into the iSCSI packet;
forwarding the packet as translated to a second device; and
wherein said translating steps are performed without buffering of the packet.
19. The method of claim 18 , wherein said translating steps are performed at wire speed.
20. The method of claim 18 , wherein the first device is an initiator and the second device is a target.
21. The method of claim 18 , wherein the first device is a target and the second device is an initiator.
22. The method of claim 18 , wherein the packet received is an iSCSI Command PDU and wherein the packet as translated is a Fibre Channel Command IU.
23. The method of claim 18 , wherein the packet received is a Fibre Channel XFR_RDY IU and wherein the packet as translated is an iSCSI R2T PDU.
24. The method of claim 18 , wherein the packet received is an iSCSI Write Data PDU and wherein the packet as translated is a Fibre Channel Data IU.
25. The method of claim 18 , wherein the packet received is a Fibre Channel Data IU and wherein the packet as translated is an iSCSI Read Data PDU.
26. The method of claim 18 , wherein the packet received is a Fibre Channel Response IU and wherein the packet as translated is an iSCSI Response PDU.
27. The method of claim 18 , wherein the packet received is a Fibre Channel Command IU and wherein the packet as translated is an iSCSI Command PDU.
28. The method of claim 18 , wherein the packet received is an iSCSI R2T PDU and wherein the packet as translated is a Fibre Channel XFR_RDY IU.
29. The method of claim 18 , wherein the packet received is a Fibre Channel Data IU and wherein the packet as translated is an iSCSI Write Data PDU.
30. The method of claim 18 , wherein the packet received is an iSCSI Read Data PDU and wherein the packet as translated is a Fibre Channel Data IU.
31. The method of claim 18 , wherein the packet received is an iSCSI Response PDU and wherein the packet as translated is a Fibre Channel Response IU.
32. A method for use in a system for storing and accessing data, the method comprising:
receiving at an ingress linecard a packet formatted in accordance with a first protocol, the packet destined for a virtual target with a virtual target address;
the ingress linecard retrieving information about the virtual target from a virtual target descriptor, the information including a flowID, and placing a virtual target descriptor identifier and the flowID, in a local header of the packet;
the ingress linecard forwarding the packet to a fabric, which forwards the packet to an egress linecard in accordance with the flowID;
the egress linecard using the virtual target descriptor identifier to identify information about a physical target associated with the virtual target, including whether the physical target requires a packet formatted in accordance with a second protocol, and using the information about the physical target to convert a virtual target block address to a physical target block address and to translate the format of the packet from the first protocol to the second protocol; and
the egress linecard sending the packet to the physical target using the physical target block address.
33. The method of claim 32 , wherein said egress linecard translates the format of the packet from the first protocol to the second protocol without buffering the packet.
34. The method of claim 32 , wherein said egress linecard translates the format of the packet from the first protocol to the second protocol at wire speed.
35. A set of software instructions stored on at least one medium in a switch for use in a system for storing and accessing data, which instructions are executable by a processor, the instructions including:
instructions for receiving a packet from a first device, the packet formatted in accordance with one of the iSCSI or Fibre Channel protocols;
if the packet is formatted in accordance with the iSCSI protocol, instructions for translating the packet into a Fibre Channel packet by mapping at least some of the fields from the packet formatted in accordance with the iSCSI protocol into the Fibre Channel packet;
if the packet is formatted in accordance with the Fibre Channel protocol, instructions for translating the packet into an iSCSI packet by mapping at least some of the fields from the packet formatted in accordance with the Fibre Channel protocol into the iSCSI packet;
instructions for forwarding the packet as translated to a second device; and
wherein said instructions for translating the packet by mapping at least some of the fields do not require the packet to be buffered.