topic Re: Replace disks with bigger disks in Disk

Replace disks with bigger disks

Jason Baldwin — Fri, 11 Jul 2003 09:28:52 GMT

Start:
vg01 2x 36Gb mirrored disks

End:
vg01 2x 73Gb mirrored disk

Disks are hotswapable.
Is it possible to remove one disk at a time re-mirror then add the second and mirror again to keep all data on disks?

Backups of original data will be done (but this would take time) and is not the desired replacement method (i.e. restore data onto newly created vg)

mount point can be taken down for brief periods of time ie 5 mins.

Is this possible? Are there risks?

Thanks for your help!

Jason

Re: Replace disks with bigger disks

Bernhard Mueller — Fri, 11 Jul 2003 10:22:40 GMT

Hello,

assuming your are using LVM in HP-UX you can do this ONLY if at running vgcreate vg01 the person who did that specified a high enogh value for max_pe_per_pv.

If not (which is usually the cae) you could only use the first 36GB of the larger disk in vg01 (which is certainly NOT what you want)

So most likely you will have to create a new vg with at least one of the larger disks and copy all the filesystems to the new vg....

Check vgdisplay vg01 for PE size (default is 4MB) and Max PE per PV (default is largest disk size at vgcreate divided by PE size)

Regards,
Bernhard

Re: Replace disks with bigger disks

Bernhard Mueller — Fri, 11 Jul 2003 10:40:04 GMT

Oops,

even more important: with those big disks you will have to use a larger PE size than the default 4MB. Else you might be able to create a vg with a single disk but unable to use a second disk and mirror onto it, because you would exceed the maximum # of extents allowed in a vg.... use PE size of 16MB in vgcreate.

Regards,
Bernhard

Re: Replace disks with bigger disks

Caesar_3 — Sat, 12 Jul 2003 18:07:25 GMT

Hello!

You can add the other disk and made mirror
on him then remove the mirror and take back
the disk.

Caesar