PVMOVE - replace 2 old disks with one new disk

[Neil J. Glennon]

Env: E55 running 10.20

I currently have 2 x 2GB disks (quite old)within vg01 for which I wish to replace with 1 x 4GB disk within an existing HASS.
This will then have all data disks (vg01 and vg02) on this server within the HASS. vg00 are the internal system disks.

Please comment on the abbreviated procedure I am looking to follow:

I will of course make a full backup before attemping this and have a current make_recovery tape.

1. Add new 4GB disk to vg01
2. Run pvdisplay on both old disks to display data.
3. pvmove
4. pvmove
5. Run pvdisplay again on old disks to very physical data move.
6. Run pvdisplay on new disk
7. Remove old disks from vg01

Any tips or comments most appreciated.

Leon.

[James R. Ferguson]

Leon:

Your plan looks fine. I think the use of pvdisplay to verify the outcome of each step is prudent. You could also do a 'vgdisplay -v vg01' before and after as well as a verbose (-v) 'lvdisplay' of each logical volume, makeing note that logical extents are allocated in the correct number and only on the "new" physical disk only when you are done.

...JRF...
...JRF...

[Andreas Voss]

Hi,

the only problem i see is the value of MAX PE at your vg01.
If it's not increased by option at vg creation time you will have not enough MAX PE for adding 4GB disk to the vg. Instead it will only take 2GB to the vg.
There is no way to modify the MAX PE on the fly. You have to recreate the vg.

Regards

[John Palmer]

Hi,

I suspect that you will get away with the MAX PE for the volume group as the default is 1016. However step 4 of your plan will fail because old disk 2 is not in vg01 - pvmove can only operate on volumes within the same volume group.

You'll have to create new volumes/filesystems to replace the current vg02 data and copy them over.

Another option is to create a new volume group on the 4Gb disk and copy both vg01 and vg02 to it - I use find/cpio. This is pretty much a no-risk strategy using temporary mount points. Having mounted the new volumes to replace the current ones and tested everything out, you can then trash the current vg01 and vg02. If there are any problems (unlikely) then you still have the original volumes to revert to.

Regards,
John