Configuring SRP Devices With COMSTAR

The SCSI RDMA Protocol accelerates the SCSI protocol by mapping the SCSI data transfer phases to Infiniband (IB) Remote Direct Memory Access (RDMA) operations. As a result, an SRP initiator can read and write data from a COMSTAR SRP target at high data rates with relatively low CPU utilization.

You can set up and configure a COMSTAR SRP target and make it available over an Infiniband (IB) fabric. The SRP target is available wherever a supported IB Host Channel Adapter (HCA) is installed on the target system.

• One SCSI target per IB HCA – The COMSTAR SRP target uses a simple model in which each supported IB HCA is registered as a SCSI target. The SCSI target is a virtual object that contains a task router and acts as a the connection between the SCSI transport (in this case, SRP) and the SCSI back end (STMF and SBD).

  An HCA can contain multiple physical ports. The same SCSI target is shared between all the ports of an HCA. The SCSI target representing the HCA is automatically available for incoming connections through all the active ports of that HCA.

• SRP target eui identifier – In the IB architecture, each HCA and each port is assigned a 64-bit GUID by the manufacturer. The COMSTAR SCSI target created for each HCA is given a name corresponding to the GUID of that HCA, which has the format: eui.HCA-GUID. For example, if the target system includes a supported IB HCA with an HCA GUID of 0003BA0001002E48, then a SCSI target will be created using the name eui.0003BA0001002E48. The string eui stands for extended unique identifier and names a class of GUIDs that is used in both the SCSI and IB standards.

• SRP initiator eui identifier – Similarly, SRP uses a 64-bit initiator GUID to identify the initiator system. The choice of which GUID to use is determined by the SRP initiator implementation. Many initiators use the GUID of the HCA that is being used for the outgoing connection. For example, an initiator using the GUID of 0003BA0001002EA5 is known to COMSTAR as eui.0003BA0001002EA5.

Using COMSTAR Views With SRP

The COMSTAR view facility can be used to create target groups and host groups that restrict and configure which logical units (LUs) can be accessed through each SCSI target or initiator as described in Making SCSI Logical Units Available. The eui identifier of the SRP initiator is added to a host group. The eui identifier of the SRP SCSI Target is added to a target group. The view entries for each LU then determine the particular set of LUs that each initiator can access.

How to Enable the SRP Target Service

The COMSTAR port provider for the COMSTAR SRP target is managed by the Service Management Facility (SMF). The primary SRP target service is svc:/system/ibsrp/target:default, which can be abbreviated to ibsrp/target.

The SRP package is storage/scsi-rdma/scsi-rdma-target.

1. Become an administrator.
2. Recursively enable the SRP target service.

   # svcadm enable -r ibsrp/target

3. Display the SRP target service information.

   # svcs -l ibsrp/target

How to Verify SRP Target Status

1. Become an administrator.
2. Verify the presence of the expected SRP SCSI target on the system.

   # srptadm list-target
   Target HCA 21280001A0D0F0:
       Enabled             : true
       SRP Target Name     : eui.0021280001A0D0F0
       Operational Status  : online