topic LVREDUCE in Operating System - HP-UX

LVREDUCE

GPissutto — Tue, 04 May 2010 19:39:29 GMT

Hello everyone,
I have dicovered that a mirrored LVOL between two storage array is actually misconfigured, it means that some parts of the mirror are in one array (the PV1 and PV2 columns), so if one of the array fails, everything fails. This LVOL is created from multiple PVOLs (16 for one array and other 16 for the second array). So I created a second mirror copy in one of the array in order to fix this problem. The thing is that I want to fix this properly and eliminate those misconfigured LEs pointing to the same PV. If I erased those 32 misconfigured PVs, lefting only those 16 new which I am sure are good. After lvreduce, is it everything to be operational?. I've tryed with a small lab and it works, but doing it live for a production system is something else...

Thanks very much for any hint.

Re: LVREDUCE

R.O. — Tue, 04 May 2010 20:35:13 GMT

Hi,

You should have no problems, but to be sure it would be good that you attached the output of "lvdisplay -v /dev/vgXX/lvolX"

Regards,

Re: LVREDUCE

GPissutto — Tue, 04 May 2010 21:16:28 GMT

Thanks R.O, here is the output. Check from disk213 on.

Re: LVREDUCE

rariasn — Wed, 05 May 2010 06:20:31 GMT

Hi GPissuto,

lvreduce -m 1 /dev/vgsapdata1_p/lvsapdata1 /dev/dsk/cxtydz

rgs,

Re: LVREDUCE

R.O. — Wed, 05 May 2010 07:48:11 GMT

Hi,

You have the mirror not well configured. The logical volume has "Allocation non-strict" and this means that mirrors of a logical extent can share the same physical volume, as you can see:

--- Logical extents ---
LE PV1 PE1 Status 1 PV2 PE2 Status 2 PV3 PE3 Status 3
06398 /dev/disk/disk213 00000 current /dev/disk/disk213 00001 current /dev/disk/disk298 00000 current

This happens from disk213 on. As you have two mirrors, you should "lvreduce" disks of the two firsts columns. After that, you should change the logical volume allocation policy to "strict" and redo the mirror.

# lvreduce -m 1 /dev/vgsapdata1_p/lvsapdata1
# lvchange -s y /dev/vgsapdata1_p/lvsapdata1

And then, redo the mirror with the proper disks. Maybe you want confirmation of this procedure from other forum experts.

Regards,

Re: LVREDUCE

GPissutto — Wed, 05 May 2010 12:06:48 GMT

Yes, I noticed all that and that's why I need to fix everything. I tryed fixing it in small lab with 6 LUN (1G each) and it worked fine when I reduced the two first columns at once, but not that well if I reduced one by one. So, as you can see there are many PVs involved and I wanted some other opinion to get couraged.

Thanks very much.

Re: LVREDUCE

GPissutto — Wed, 05 May 2010 12:09:21 GMT

Anothe thing R.O, did you mean:
# lvreduce -m 0 /dev/vgsapdata1_p/lvsapdata1 ?

Cause leaving a mirror copy is the scenario that doesn't work well.

Re: LVREDUCE

R.O. — Wed, 05 May 2010 12:35:24 GMT

Yes, sorry for that. I mean "-m 0", because you don't want any mirror copy. You have to be sure of including all the pvs of the two first columns in the lvreduce command.

Regards,

Re: LVREDUCE

singh sanjeev — Wed, 05 May 2010 15:30:28 GMT

best is to do via pvmove command :

move the LV from one array to deired array..

Re: LVREDUCE

GPissutto — Fri, 07 May 2010 15:24:33 GMT

Thanks