NetWorker: Implementing Tape Device Name Persistence for Linux

Tape Devices in NetWorker are configured with the driver name the Operating System has assigned them when they are first detected and configured by NetWorker.

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

In order to ensure your Linux NetWorker Storage Nodes or Server retains a valid name for all zoned tape devices, Persistence must be configured in the Operating System.

udev is the Linux component that governs this and it is freely downloadable. Downloading, installing and implementation are the responsibility of the Administrator and problems encountered should be referred to the appropriate Linux vendor for support.

Before installing udev, running the NetWorker command inquire -lscp command returns devices appearing like this:

scsidev@1.2.0:IBM     ULTRIUM-TD3     54K1|Tape, /dev/nst0

Implementing udev using yum

1. On your Linux host, open a command prompt
2. Run yum install udev (note - different Linux distributions may use different package managers)
3. Answer yes to prompts to proceed
4. Ensure udev service is started - reboot if necessary
5. Retry inquire -lscp and look for long or persistent name:

scsidev@1.2.0:IBM     ULTRIUM-TD3     54K1|Tape, /dev/tape/by-id/scsi-350060b0036323639-nst

Next actions 

In the NetWorker Management Console (NMC) you have two choices: 

1. Reconfiguration preserving existing Library instance (preserves existing Library settings)
   • Right-click and Reconfigure Library instance
   • Clear all but one device, then click Configure
   • Delete the orphaned Tape device instances from the Devices container
   • Scan for devices for the affected Nodes to rediscover new Tape device names
   • Reconfigure Library, checking all new Tape device instances, and clearing the remaining Tape - then select Configure
   • Finally, delete that last Tape's instance from Devices and rescan/reconfigure a second time, this time adding the last device
2. Full library recreation (review specific configuration items before, like Cleaning, Features, Timers, Auto Media Management, so forth)
   • Delete Library instance, and all Tape devices belonging to that instances afterward, from the Devices container
   • Scan for devices for the affected Nodes to rediscover new device names
   • Reconfigure Library, checking all new instances, and select Configure
   • After completion, ensure any Library configuration details required are replaced, like Cleaning Tape, Features or Timers changes, so forth

From this point on - you should no longer need to worry about tape device names changing below the application layer, invalidating the names configured in NetWorker.