You can obtain the iSCSI statistics that are displayed when you run the iscsi stats command. For vFiler contexts, the statistics displayed refer to the entire storage system, not the individual vFiler units.
iSCSI PDUs received
The iSCSI Protocol Data Units (PDUs) sent by the initiator include the following statistics:
- SCSI-CMD
- SCSI-level command descriptor blocks.
- LoginReq
- Login request PDUs sent by initiators during session setup.
- DataOut
- PDUs containing write operation data that did not fit within the PDU of the SCSI command. The PDU maximum size is set by the storage system during the operation negotiation phase of the iSCSI login sequence.
- Nop-Out
- A message sent by initiators to check whether the target is still responding.
- Logout-Req
- Request sent by initiators to terminate active iSCSI sessions or to terminate one connection of a multi-connection session.
- SNACK
- A PDU sent by the initiator to acknowledge receipt of a set of DATA_IN PDUs or to request retransmission of specific PDUs.
- SCSI TaskMgtCmd
- SCSI-level task management messages, such as ABORT_TASK and RESET_LUN.
- Text-Req
- Text request PDUs that initiators send to request target information and renegotiate session parameters.
iSCSI PDUs transmitted
The iSCSI PDUs sent by the storage system include the following statistics:
- SCSI-Rsp
- SCSI response messages.
- LoginRsp
- Responses to login requests during session setup.
- DataIn
- Messages containing data requested by SCSI read operations.
- Nop-In
- Responses to initiator Nop-Out messages.
- Logout-Rsp
- Responses to Logout-Req messages.
- R2T
- Ready to transfer messages indicating that the target is ready to receive data during a SCSI write operation.
- SCSI TaskMgtRsp
- Responses to task management requests.
- TextRsp
- Responses to Text-Req messages.
- Asyncmsg
- Messages the target sends to asynchronously notify the initiator of an event, such as the termination of a session.
- Reject
- Messages the target sends to report an error condition to the initiator, for example:
- Data Digest Error (checksum failed)
- Target does not support command sent by the initiator
- Initiator sent a command PDU with an invalid PDU field
iSCSI CDBs
You can obtain statistics associated with handling iSCSI Command Descriptor Blocks, including the number of blocks of data transferred, and the number of SCSI-level errors and successful completions.
iSCSI Errors
You can obtain a list of login failures and other SCSI protocol errors.