NetWorker: Implementing Tape Device Name Persistence for Windows

Tape devices in NetWorker are configured with the driver name the Operating System has assigned them when NetWorker first detects and configures them.

Several events may cause the Operating System to change the devices' names such as Host or device reboot, temporary connectivity loss, SAN reconfiguration, and others.

In order to ensure your Windows NetWorker host retains a valid name for all zoned tape devices, Persistence must be configured in the Operating System.

There are two different and supported methods which may be used, depending on the driver that is installed. In Device Manager, locate the device and in Properties, under the Driver tab, click Driver Details button. The .sys file listed is the same as the registry key where the changes are made.

IBM drivers use a different, driver-specific registry key. All others use an OS generic key for this change.

IBM driver (ibmtp*)

1. Open the registry with regedit command
2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\ibmtp*
3. Create a DWORD value (case sensitive): PersistentNaming with value of 1

All other drivers

1. Open the registry with regedit command
2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Tape
3. Create a DWORD value (case sensitive): Persistence with value of 1

When this is complete, run inquire -slc and confirm that the Tape devices now show a longer name (for example, instead of \\.\Tape0, it now shows \\.\Tape21474056).

Next actions

1. Open Device Manager using devmgmt.msc and disable then reenable all tape devices. This makes the new, persistent device names available for NetWorker to use. 
2. In NMC, there are two ways to reconfigure:
   • Reconfiguration preserving existing Library instance (preserves existing Library settings):
     1. Right-click and Reconfigure Library instance
     2. Clear all but one device, then click Configure
     3. Delete the orphaned Tape device instances from the Devices container
     4. Scan for devices for the affected Nodes to rediscover new Tape device names
     5. Reconfigure Library, checking all new Tape device instances, clearing the remaining Tape, and then select Configure
     6. Delete that last Tape's instance from Devices and rescan or reconfigure a second time, this time adding the last device
   • Full library recreation (review specific configuration items before, like Cleaning, Features, Timers, Auto Media Management, so forth)
     1. Delete Library instance, and all Tape devices belonging to that instances afterward, from the Devices container
     2. Scan for devices for the affected Node to rediscover new device names
     3. Reconfigure Library, checking all new instances, and select Configure
     4. After completion, ensure any Library configuration details required are replaced, like Cleaning Tape, Features or Timers changes, so forth

After configuration of persistent names, tape device names no longer change below the application layer. This prevents future issues with device naming in NetWorker.
 

• udev is the equivalent Persistent Naming package installable to Linux.
• HP-UX, Solaris, and AIX tape devices are all configured persistently to begin with and do not require these measures.
• This does NOT prevent connectivity loss to devices, but ensures name consistency.
• Protection does not extend to the tape or robot SCSI addresses. Because the SCSI address for the changer is used, library control operations are still affected if the SCSI address changes.