RH Switching rootvg/sanvg to New SAN

Linux and Unix-Like Linux
1

Hi, what's the safest procedure to reconfigure RH BFS to a new SAN?

Current setup boots rootvg and sanvg from a SAN.
Now a new SAN LUN is presented to the Linux Server.
The first and second SAN are srdf'd - so they are always in sync.

Can I re-use the existing LVM structure and somehow switch the underlying devices to the new LUNs?

Or, do I have to start from scratch, create new luns, re-build LVM, and re-install RH?

Urgent - this is scary. Thanks.

2

When I have migrated LVM managed volumes in the past, we would:-

  • Present the new LUNs
  • Grow the volume groups be adding the new LUNs
  • Use pvmigrate, pvmove or migratepv (as appropriate to the OS to move the logical volumes from the old to the new LUNs
  • Remove the old (empty) LUNs from the volume group
  • Remove the old LUNs from the OS
  • Remove the old LUNs from the old SAN

The boot volume group is rather trickier and you may have to do some when booted from CD, else the devices will be in use. You would probably need to edit the grub, however I have not had to do this as we were always local boot and just the data volume groups were moving.

There is commercial software that may assist you with this, such as that from Storix (see https://www.youtube.com/user/StorixSoftware and Linux, AIX and Solaris Backup and System Recovery Software) or Christie Clone Manager (see Cristie and Cristie Software CloneManager) that may help. If it's a one-off, you might even manage the process with the demo software, but perhaps it would be worth investing in one of them anyway.

I hope that this helps,
Robin

3

Hi, wow that sounds awesome - thanks for the insights.

This is a live production server I have to work with - any chance you know how to accept the new LUN presentations on RH - and how to write the pvmigrate command?

The entire rootvg including /boot is on the SAN - so do you think the pvmigrate will cover the /boot as well - or will I have to create a new /boot on the new SAN?

4

I regret that I have not moved the boot volume group before and don't have a server I can try it on available. I would have to defer to those wiser than I on the procedure to follow. Have you approached Red Hat themselves for advice? They are normally very good. It depends on your support contract I suppose.

It might be relatively simple, something like:-

  • Boot from CD (or image)
  • Slice new LUN to create /boot and LVM partitions
  • Copy /boot from old to new
  • Vary on & extend the boot volume group with the new LUN
  • Migrate (as above)
  • Alter the boot parameter and/or grub.conf
  • Shutdown & boot.

Of course I can't be sure and I would not know how to alter the boot parameters and/or grub.conf so more advice is required.

Robin