Edit: When was the last time you had to worry about this?
Originally posted April 7, 2020 on AIXchange
Rob McNelly walks through customer troubleshooting from an IBM Redbook.
A client was looking to repurpose and virtualize an old TS3200 tape library. The idea was to connect it to a VIO server and then assign it to their IBM i clients.
However, errors came up when running cfgdev:
cfgmgr: 0514-621 WARNING: The following device packages are required for device support but are not currently installed.
devices.sas.changer
After downloading atape drivers from IBM Fix Central and loading them on the LPAR, the errors went away. An scm0 and some rmt* devices could be seen.
# lsdev -Cc tape
rmt0 Available 06-00-00 IBM 3580 Ultrium Tape Drive (SAS)
rmt1 Available 06-00-00 IBM 3580 Ultrium Tape Drive (SAS)
rmt2 Available 06-00-00 IBM 3580 Ultrium Tape Drive (SAS)
rmt3 Available 06-00-00 IBM 3580 Ultrium Tape Drive (SAS)
smc0 Available 06-00-00 IBM 3573 Library Medium Changer (SAS)
However, more errors emerged with an attempt to use mkvdev to assign the drive to the client LPAR. It took some searching to sort it all out.
First, this tip (scroll down):
You can virtualize SAS tape drives, but only per-LPAR. Meaning, on VIOS it shows Available, then you “mkvdev -vdev rmt0 -vadapter vhostx -dev vrmt0” as padmin ID. This will work ONLY if no atape is installed on VIOS.
Then this reminder from IBM Support:
Note 1: The VIOS cannot use Atape drive, such as the 3580, when attempting to virtualize a SAS tape drive to AIX client.
And finally, another forum comment:
… You cannot virtualize the 3100. In fact, you cannot virtualize any medium changer. You have to get rid of the virtual layer and assign a dedicated adapter to the LPAR and connect the 3100. Then you will have rmt0 and smc0.
Also, do not install Atape drivers on VIOS. This causes havoc on your virtual layer. If Atape is installed, then you will not be able to share the tape drive by mapping it to LPARs.
For completeness, refer to this IBM Redbook.
In this case, once they removed the devices, removed the drivers, reran cfgdev and then reran the mkvdev commands, it worked as expected.
I realize only a handful of people will ever deal with this issue, but I believe whenever a problem is solved, the solution is worth sharing.