Intelligent Storage Services Configuration Guide, Cisco DCNM for SAN, Release 7.0.x

SCSI Flow Statistics Overview

The statistics that can be collected for SCSI flows include the following:

• SCSI reads

– Number of I/Os

– Number of I/O blocks

– Maximum I/O blocks

– Minimum I/O response time

– Maximum I/O response time

• SCSI writes

– Number of I/Os

– Number of I/O blocks

– Maximum I/O blocks

– Minimum I/O response time

– Maximum I/O response time

• Other SCSI commands (not read or write)

– Test unit ready

– Report LUN

– Inquiry

– Read capacity

– Mode sense

– Request sense

• Errors

– Number of timeouts

– Number of I/O failures

– Number of various SCSI status events

– Number of various SCSI sense key errors or events

To take advantage of this feature, only the initiator must be directly attached to an SSM.

Note The SCSI flow statistics feature requires the Enterprise Package license installed only on the initiator switches.

Note For SCSI flow statistics, the initiator must connect to an SSM on a Cisco MDS switch while the target can connect to any other switch in the fabric. The SCSI flow initiator and target cannot connect to the same switch.

SCSI Flow Specification Attributes

A SCSI flow specification consists of the following attributes:

• SCSI flow identifier
• VSAN identifier
• SCSI initiator port WWN
• SCSI target port WWN
• Flow feature set consisting of Fibre Channel Write Acceleration and statistics monitoring.

SCSI Flow Manager

The SCSI flow manager (SFM) resides on a supervisor module and handles the configuration of SCSI flows, validating them and relaying configuration information to the appropriate SSM. It also handles any dynamic changes to the status of the SCSI flow due to external events. The SFM registers events resulting from operations, such as port up or down, VSAN suspension, and zoning that affects the SCSI flow status, and updates the flow status and configuration accordingly.

The SFM on the initiator communicates to its peer on the target side using Cisco Fabric Services (CFS). Peer communication allows the initiator SFM to validate target parameters and program information on the target side.

SCSI Flow Configuration Client

A SCSI flow configuration client (SFCC) resides on the CPP of the SSM. It receives flow configuration requests from the SFM, programs the DPP corresponding to the initiator and target port interfaces, and responds to the SFM with the status of the configuration request.

SCSI Flow Data Path Support

The DPP on the SSM examines all the messages between the initiator and target and provides SCSI flow features such as Fibre Channel Write Acceleration and statistics monitoring.

Enabling SCSI Flow Statistics

Detailed Steps

To enable SCSI flow statistics monitoring using DCNM-SAN, follow these steps:

Step 1 Expand End Devices and then select SSM Features in the Physical Attributes pane.

You see the FCWA tab in the Information pane.

Step 2 Click Create Row in the Information pane to create a SCSI flow or click a row in the FCWA table to modify an existing SCSI flow.

You see the FC Write Acceleration dialog box.

Step 3 Select the initiator and target WWNs and VSAN IDs and check the Enable Statistics check box to enable SCSI flow statistics on this SCSI flow.

Step 4 (Optional) Enable Fibre Channel Write Acceleration on this SCSI flow at this time by checking the WriteAcc check box.

Step 5 Click Create to create this SCSI flow.

Clearing SCSI Flow Statistics

Clears SCSI flow statistics counters for SCSI flow ID.

Detailed Steps

To clear SCSI flow statistics using DCNM-SAN, follow these steps:

Step 1 Expand End Devices and then select SSM Features.

Step 2 Check the Stats Clear check box to clear SCSI flow statistics.

Step 3 Click the Apply Changes icon to clear the SCSI flow statistics.

SSM

Virtual Initiator