topic Re: Mirroring Problems/Alternatives in Operating System - HP-UX

Mirroring Problems/Alternatives

Johns Manville — Fri, 08 Oct 2010 16:54:46 GMT

I have HP-UX 11.11 using disk from EVA SAN. I am moving the server from EVA1 to EVA2 by mirroring the existing EVA1 disks to new disks added to the VG from EVA2.

However, on some of my VGs, the Max_PE_per_PV is set too low. I don't want to try vgmodify2, since it's unsupported in 11.11.

Is it possible to add the new disk to the VG and then just do a pvmove to copy from the old EVA1 to the new EVA2?

Or, instead of trying to add a disk that is too large, can I add 3 smaller disks and mirror to them? I'm not sure how mirroring an lvol to three disks would work.

Thanks,

Re: Mirroring Problems/Alternatives

Patrick Wallek — Fri, 08 Oct 2010 17:09:30 GMT

>>Is it possible to add the new disk to the VG
>>and then just do a pvmove to copy from the
>>old EVA1 to the new EVA2?

Yes, this is definitely possible. If you do a 'pvmove' just try to make sure that it does not get interrupted before it finishes. If a 'pvmove' does get interrupted it can be somewhat difficult to get the LV back to a clean state.

>>Or, instead of trying to add a disk that is
>>too large, can I add 3 smaller disks and
>>mirror to them? I'm not sure how mirroring
>>an lvol to three disks would work.

That is possible as well. You just do your normal 'lvextend -m 1' and LVM will take care of determining what disks to use. If you want more control, you can tell LVM what disks to use when mirroring by specifying them on the command line. For example if you want to mirror VG01/LVOL1 to c1t1d1 and c1t1d2, you would do:

# lvextend -m 1 /dev/vg01/lvol1 /dev/dsk/c1t1d1 /dev/dsk/c1t1d2

Re: Mirroring Problems/Alternatives

Johns Manville — Fri, 08 Oct 2010 17:24:07 GMT

Thank you sir.

Re: Mirroring Problems/Alternatives

singh sanjeev — Fri, 08 Oct 2010 17:24:28 GMT

add to above step, once mirroring is done break the mirroring of LV with EVA1 disk...via

lvextend -m 0

after that vgreduce the EVA1 disk from VG..

Re: Mirroring Problems/Alternatives

Johns Manville — Fri, 08 Oct 2010 17:26:44 GMT

I was aware of that part, but you are right and thanks for mentioning it.