Missing Logical Volume Label! Doco Saved the Day!
AdrianMahendrata 2700008J7X Comment (1) Visits (5523)
I was asked to move data on SAN LUNs from one LPAR (source LPAR) to another (destination LPAR). What normally is an easy task turned to a rather “troublesome” one for me.
As many would agree, the sensible steps to accomplish this are:
All the steps went error free. However, when I got to step 7 – mounting the file system – I quickly realised that the Logical Volume in the Volume Group has no mount points. My initial reaction was … bummer!!
The lsvg –l command output was showing the below:
After a quick investigation, I noticed that the Logical Volumes (LV) are missing their labels. How did I know? Well, I used the getlvcb command as shown below:
Why is the LV label missing?
Well, that’s a good question. The LPAR had undergone a data centre move using third-party software in the past. As part of migration, the LVM components (VG, LV & FS) configuration was re-created by the third-party software. I suspect that the issue could very well be introduced at the time.
Well, the fix is quite simple. Those Logical Volumes need to have a label assigned to them. The label would be the file system name that sits on the Logical Volume.
Steps taken to fix this:
Once the above was done, the Logical Volumes will have a mount point and I was able to mount all the file systems without any data loss or corruption.
Importance of System Documentation!
On my environment, I’ve scheduled a script that runs regularly via cron to performs a bunch of commands to capture system information (i.e LVM, CPU, Memory, etc). The lsvg -l command is one of them. Thanks to this, I was able to map out the Logical Volume and File System relationship quite easily. I even wrote a one liner script to assign the Logical Volume labels across hundreds of file systems.
Without the system documentation, it would be a challenge mapping out which File System sits on the each Logical Volumes and it would take a very long time before the LPAR can be made available again.
Therefore if you haven’t done so, capture system configurations across your environment. It will be useful one day when you need it just as it was useful to me for this incident!!
“Adrian Mahendrata is an AIX, PowerVM, and PowerHA specialist in Melbourne, Australia. He has many years of experience in the design and implementation of AIX, PowerVM, and PowerHA across large enterprise environments. He has worked on various migration projects and disaster recovery implementations throughout his career. He enjoys photography and motorbike riding during his free time. You can connect with him on LinkedIn and follow him on Twitter @amahendrata.”