Setting persistent device names for tape devices in RHEL

Environment

• Red Hat Enterprise Linux

Issue

• We got a tape library which keeps changing name, what are the steps to set persistent names for tape devices in RHEL?
• We need to make tape devices /dev/nst* persistent for backup service. How do we configure it?

Resolution

To assign persistent name of tape devices, add a rule similar to below:

1. Go to /etc/udev/rules.d/:

# cd /etc/udev/rules.d/

2. Create new rules config file:

# vi 99-tape.rules

3. Add following rule:

ACTION=="add|change", ENV{ID_SERIAL}=="<ID_SERIAL>", SYMLINK+="my_tape_01"

4. Reload the udev configuration for changes to take effect.

This will assign name: /dev/my_tape_01 for this tape device which would be persistent across reboot. It will a symlink created for tape devices and the actual device would be intact.

Diagnostic Steps

• We can set up persistent device naming using udev rules in RHEL 7 the same as RHEL 6.

• Run the following command against the tape device to get details about the device:

    # udevadm info --query=all --name=/dev/<Tape_Device>
  

  For example:

    # udevadm info --query=all --name /dev/st0
    P: /devices/pci0000:00/0000:00:07.0/0000:0e:00.0/host8/rport-8:0-2/target8:0:0/8:0:0:5/scsi_tape/st0
    N: st0
    :
    E: ID_SERIAL=350223344ab000500
    :
  

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