MODIFICATION OF SMALL COMPUTER SYSTEM INTERFACE COMMANDS TO EXCHANGE DATA WITH A NETWORKED STORAGE DEVICE USING AT ATTACHMENT OVER ETHERNET
A process executed by a computing device uses commands having a first format to exchange data through a network with a storage device configured to execute commands having a second format. A storage device controller identifies a command type associated with a command received from the process and identifies one or more physical memory addresses associated with the command. The storage device controller identifies a command having a second format associated with the received command and generates a network request including the command having the second format, the one or more physical memory addresses, a device identifier associated with the storage device and a tag. The network request is transmitted through a network to the storage device which executes the command having the second format. For example, an AoE request including an ATA command is generated from a received SCSI command.
1 . A method for generating a network request including a second command from a first command, the method comprising:
identifying a command type associated with the first command having a first format;
determining one or more physical memory addresses associated with the first command;
generating one or more identifiers having a second format, each identifier associated with at least one of the physical memory addresses associated with the first command;
identifying the second command having the second format, the second command associated with the identified command type;
generating the network request at a computing device located across a network from a storage device configured to use the second format, the network request including a device identifier associated with the storage device, a tag, the second command and the one or more identifiers having the second format and being associated with the physical memory addresses associated with the first command having the first format; and
storing the network request in a transmission queue for transmission over the network from the computing device to the storage device.
2 . The method of claim 1 , further comprising:
receiving a network response comprising a response tag;
comparing the response tag to the tag of the network request;
determining that the tag matches the response tag; and
associating the network response with the network request.
3 . The method of claim 1 wherein the first format comprises a Small Computing System Interface (“SCSI”) format.
4 . The method of claim 1 wherein the second format comprises an AT Attachment (“ATA”) format.
5 . The method of claim 1 , wherein the network request comprises an AT Attachment over Ethernet (“AoE”) request.
6 . The method of claim 1 , wherein identifying the command type associated with the first command comprises:
determining an opcode included in the first command.
7 . The method of claim 1 , wherein generating the identifier associated with the at least one physical memory address associated with the first command comprises:
determining a scatter/gather list associated with the first command;
identifying a pointer included in the scatter/gather list;
determining a physical memory address associated with the pointer; and
generating a first identifier associated with the physical memory address associated with the pointer.
8 . The method of claim 1 , wherein storing the network request in the transmission queue comprises:
storing a copy of the device identifier associated with the storage device;
storing a copy of the tag; and
associating the copy of the tag with the copy of the device identifier.
9 . The method of claim 1 , wherein storing the network request in the transmission queue comprises:
determining a congestion level associated with each of a plurality of transmission queues;
identifying a transmission queue from the plurality of transmission queues having a minimum congestion level when compared to the remaining transmission queues in the plurality of transmission queues; and
storing the network request in the transmission queue from the plurality of transmission queues having the minimum congestion level.
10 . The method of claim 1 , wherein the device identifier comprises a major address and a minor address associated with the storage device.
11 . A computer readable storage medium for storing a computer program product including instructions executable by a processor of a computing device to perform a computer implemented method for generating a network request including a second command from a first command, the method comprising:
identifying a command type associated with the first command having a first format;
determining one or more physical memory addresses associated with the first command;
generating one or more identifiers having a second format, each identifier associated with at least one of the physical memory addresses associated with the first command;
identifying the second command having the second format, the second command associated with the identified command type;
generating the network request at a computing device located across a network from a storage device configured to use the second format, the network request including a device identifier associated with the storage device, a tag, the second command and the one or more identifiers having the second format and being associated with the physical memory addresses associated with the first command having the first format; and
storing the network request in a transmission queue for transmission over the network from the computing device to the storage device.
12 . The computer readable storage medium of claim 11 , wherein the computer implemented method further comprises:
receiving a network response comprising a response tag;
comparing the response tag to the tag of the network request;
determining that the tag matches the response tag; and
associating the network response with the network request.
13 . The computer readable storage medium of claim 11 , wherein the first format comprises a Small Computing System Interface (“SCSI”) format.
14 . The computer readable storage medium of claim 11 wherein the second format comprises an AT Attachment (“ATA”) format.
15 . The computer readable storage medium of claim 11 , wherein the network request comprises an AT Attachment over Ethernet (“AoE”) request.
16 . The computer readable storage medium of claim 11 , wherein identifying the command type associated with the first command comprises:
determining an opcode included in the first command.
17 . The computer readable storage medium of claim 11 , wherein generating the identifier associated with the at least one physical memory address associated with the first command comprises:
determining a scatter/gather list associated with the first command;
identifying a pointer included in the scatter/gather list;
determining a physical memory address associated with the pointer; and
generating a first identifier associated with the physical memory address associated with the pointer.
18 . The computer readable storage medium of claim 11 , wherein storing the network request in the transmission queue comprises:
storing a copy of the device identifier associated with the storage device;
storing a copy of the tag; and
associating the copy of the tag with the copy of the device identifier.
19 . The computer readable storage medium of claim 11 , wherein storing the network request in the transmission queue comprises:
determining a congestion level associated with each of a plurality of transmission queues;
identifying a transmission queue from the plurality of transmission queues having a minimum congestion level when compared to the remaining transmission queues in the plurality of transmission queues; and
storing the network request in the transmission queue from the plurality of transmission queues having the minimum congestion level.
20 . The computer readable storage medium of claim 11 , wherein the device identifier comprises a major address and a minor address associated with the storage device.