Cisco MDS SanOS Troubleshooting Guide -- Troubleshooting SAN Device Virtualization

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This section describes how to troubleshoot and resolve SAN device virtualization (SDV) configuration issues in the Cisco MDS 9000 Family of multilayer directors and fabric switches.



With Cisco SDV, you can create virtual devices that represent physical end-devices. The SAN devices that are virtualized can be either initiators or targets. Virtualization of SAN devices accelerates swapout or failover to a replacement disk array, and it also minimizes downtime when replacing host bus adapters (HBAs) or when re-hosting an application on a different server.

Troubleshooting SDV involves checking the configuration of virtual devices, domain IDs, and zone sets. Configuration problems with SDV can prevent devices from communicating properly.

Note Note: SDV is a distributed service and uses CFS (Cisco Fabric Services) distribution to synchronize the databases.

Initial Troubleshooting Checklist

Begin troubleshooting SDV issues by checking the following issues:


Check off

Verify licensing requirements. See Cisco MDS 9000 Family Fabric Manager Configuration Guide.

Enable SDV on all the relevant switches.

Configure the virtual devices (with or without a persistent FC ID) in a VSAN.

Link the virtual device with the primary real device.

Commit the configuration in the VSAN and check the commit status.

Ensure that the SDV database is consistent on all switches.

Ensure that the virtual devices are zoned correctly.

Activate the zone set.

For a host/virtual device connected to a Cisco MDS 9124 Fabric Switch, ensure that there is a rewrite-capable SDV-enabled director switch in the path.

Debugging and Verifying SDV Configuration Using the CLI

Several commands involving multiple configuration tasks can be used to debug and verify the SDV configuration. Table 12-1 lists debugging and verification CLI commands.

Table 12-1 CLI Commands for Debugging and Verification of SDV

CLI Command


show sdv database

Displays the SDV virtual device configuration that has been committed.

show sdv session status

Displays the status of the last CFS operation in the SDV configuration.

show sdv merge status

Displays the status of the last CFS merge.

show sdv internal acl-cache dump

Displays SDV ACL entries programmed on interfaces.

show sdv zone active

Displays the SDV zones in the active zone set.

debug sdv all-sdv

Configures all filters for SDV debugging.

show tech-support sdv

Displays most SDV-related debugging information.

SDV Limitations and Restrictions

Be aware of the following limitations and restrictions of SDV:

  • All SDV devices, and the real devices accessing the SDV devices, must to be attached to SDV enabled switches.
  • SDV does not work for devices connected to non-MDS switches.
  • Broadcast zoning is not supported for a zone with a virtual device.
  • IVR and SDV cannot be used for the same device. In other words, a SDV-virtualized device cannot be part of a IVR zone or zoneset.
  • Virtual device names should be unique across VSANs because they are registered with the device alias server, which is unaware of VSANs. For example, if you have enabled SDV and have registered a name, vt1 in both VSAN 1 and VSAN 2, then the device alias server cannot store both entries because they have the same name.
  • You cannot specify the same primary device for different virtual devices.
  • SDV works in a hard zoning environment only. (Hard zoning is enforced using ACLs that are applied by the switch port ASIC to every Fibre Channel frame that is switched; hard zoning is also referred to as port zoning.) SDV does not work in the default zone, even if you set it to permit.
  • The real device-virtual device zone cannot coexist with the real device-real device zone. If the real devices are not already zoned together, then you can configure the real device-virtual device zone with no negative impact. If these devices are already zoned, then adding the real device-virtual device zone may cause the zone activation to fail. If this occurs, then you must delete one of the zones before activation.
  • There must be at least one rewrite-capable SDV-enabled MDS switch located between the server and the target that is being virtualized. The Cisco MDS 9124 Fabric Switch is not a rewrite-capable switch.

In other words, SDV does not work when real devices and primary virtual devices are connected to the same Cisco MDS 9124 Fabric Switch.

Caution Caution: When restoring a configuration file from an ASCII file (for example, when you issue the copy bootflash:saved-config running-config command), ensure that the pWWNs in the device alias configuration portion of the file are consistent with the current fabric state. If pWWNs in the saved configuration file do not match the current fabric state, then it can result in inconsistencies and merge failures of SDV (which can occur if the file being used to restore the configuration was saved at some earlier point, and subsequent changes have been made to the device alias database). If this occurs, edit the saved configuration file to make the device-alias pWWNs consistent with the device aliases currently used in the fabric.

SDV Issues

SDV Commit Fails

SDV Commit Partially Fails

Host Cannot Locate Disk

SDV Merge Fails When ISL Comes Up

Zone Activation Fails in a SDV Zone

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