topic Re: replace disk in mirrored stripeset ? in Operating System - HP-UX

replace disk in mirrored stripeset ?

Christian Schulze — Tue, 06 May 2003 10:00:20 GMT

Hi peers,
I have to replace a failed Hot-Swap-disk in a mirrored stripeset. I read the man pages, but could not find my special(?) case.

I use extend-based mirrored stripes. The Volume was created this way:

Volumegroup
vgcreate -g PVG0 /dev/vgdb /dev/dsk/c1t3d0 /dev/dsk/c1t2d0

vgextend -g PVG1 /dev/vgdb /dev/dsk/c4t3d0
vgextend -g PVG1 /dev/vgdb /dev/dsk/c4t2d0

and LV
lvcreate -D y -s g -m 1 -L 500 -n oradata /dev/vgdb

so as far as I know you can create this only in one single step. It is not possible to first create a stripe set over some disks and afterwards mirroroing this set on some other disks ...

Now I need to replace one disk ... the manual says to reduce the disk from the vg, replace it, and mirror it back onto

this seems to be a contradiction to me

So what would be the right steps for me ?

Christian

Re: replace disk in mirrored stripeset ?

LucianoCarvalho — Tue, 06 May 2003 10:07:03 GMT

hi,

I follow this steps when I have to replace a mirror disk.

1 - Replace the disk

2 - restore lvm information
#vgcfgrestore -n /dev/vgxx /dev/dsk/cxtxdx

3 - reactivate the vg
#vgchange -a y vgxx

4 - resync the vg
#vgsync vgxx

best regards

Re: replace disk in mirrored stripeset ?

Armin Feller — Tue, 06 May 2003 10:11:36 GMT

An easy way to do this is like follows (not realy supported and only if you have a hot-swap-disk):

?? remove the disk you want to change
?? run 'vgchange -a y vgXY'
?? insert the new disk
?? run 'vgchange -a y vgXY' again
?? run 'vgcfgrestore ...'
?? run 'vgsync vgXY'

Regards ...
Armin

Re: replace disk in mirrored stripeset ?

Christian Schulze — Tue, 06 May 2003 10:18:26 GMT

Thanks

I would like to do it this way, but all manuals keep saying first to lvreduce ...

I have a running Oracle DB in this vg which is very important to us.

Of course I have a backup, archivelogs and all other things needed for a recovery (and it worked some weeks ago)

I think I will try it tomorrow morning ...

Christian

- I will assign points tomorrow after lunch !

Re: replace disk in mirrored stripeset ?

Patrick Wallek — Tue, 06 May 2003 12:34:40 GMT

There is absolutely no reason to lvreduce / vgreduce the bad disk out of the VG. It may not work anyway if the disk it totally bad.

The steps you have been given work and work quite well.

For more information check out the "Software Recovery Handbook" located here: http://www2.itrc.hp.com/service/iv/node.do?node=prod%2FWW_Start%2FN1%7C16 and check out "Chapter 16: LVM". It goes over the steps to recover hot swap drives, though it, too, says to lvreduce, which I disagree with.

Re: replace disk in mirrored stripeset ?

Christian Schulze — Thu, 08 May 2003 11:01:29 GMT

Thanks to all

vgcfgrestore and vgsync worked

This saved my weekend ...

Christian