Extending mirrored logical volume

[panks]

Hi,
I want to extend /var file system by 500MB.
When I checked with vgdisplay -v vg00 I found that its mirrored as PV used are showinf as 2.
Can you please tell me how I can extend the file system for mirrored volume. I think fsadm would be the command but not sure for mirrored volume.
Thanks

[SUDHAKAR_18]

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=949621

[Steven E. Protter]

Shalom,

Break the mirror.

lvextend -m 0
lvsplit can also be used.

lvextend -M

lvextend -m 1 < logical volume name> < disk name(s)> to rebuild the mirror.

Not breaking the mirror might lead to incomplete mirroring, or the logical volume not being complete in the event of a lost disk.

You would to extend the file system itself need to umount /var and run extendfs unless you have online JFS.

See Berd's response in this thread:
http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1080381

fsadm -F vxfs -b M

SEP

[Roopesh Francis_1]

remove strict allocation using
#lvchange -C n lvname
split the logical volume
#lvsplit lvname
extend the logical volume
#lvextend -L size lvname
#lvextend -L size lvnameb
merge the logical volume
#lvmerge lvname lvnameb
extend the file system
#fsadm -F vxfs -b M fs

[R.K. #]

Hi Panks,

You already got different procedures to extend /var when it is mirrored.

NOte: Used PV in vgdisplay can be 2 but that does NOT mean it is mirrored.....check with "lvdisplay /dev/vg00/xxxx" and look for mirror copies, if it is one that means its mirrored.

Regds,
R.K.

[R.K. #]

Also before extending you can check the "Free PE" in vgdisplay o/p to know the free space available in the VG.

Regds,
R.K.

[James R. Ferguson]

Hi:

> SEP: Break the mirror. Not breaking the mirror might lead to incomplete mirroring, or the logical volume not being complete in the event of a lost disk.

What?!? There is NO NEED to break the mirror to extend the logical volume! This unnecessarily complicates your actions and creates a window (albeit small) where you have no high-availability and data protection.

To extend a filesystem housed in a mirrored logical volume, 'lvextend' the logical volume. All mirrors by default will be extended too. Then, enlarge the filesystem using 'fsadm' if you have OnlineJFS. If you lack OnlineJFS boot into single user mode and using the commands in '/sbin' perform an 'lvextend' and and 'extendfs'. A reboot afterwards is the simplest way to resume normal operations.

To see if a _logical_volume_ is mirrored, do:

# lvdisplay /dev/vgNN/lvolX

Look for "Mirror copies" greater than zero (0). If the number of mirror copies exceeds zero, the logical volume is mirrored.

Adding '-v' to the 'lvdisplay' will show you the physical volumes on which the mirrored extents live.

Regards!

...JRF...

[Sharma Sanjeev]

Hi Panks

I agree with James, There is not need to break mirror.

1. Check for Mirror status with lvdisplay -v

than check for Free PE on Disk
than

lvextend -L 500
Than
fsadm

Regards
Sanjeev

[Patrick Wallek]

Why on earth does everyone insist on making this more complicated than it needs to be?

Saying that you need to un-mirror a mirrored LV or lvsplit a mirrored LV in order to extend it is patently ridiculous. There's absolutely no need to do any of that.

If you have free extents on ALL disks in the mirror then it is as simple as JRF has said above.

Anything else is unnecessarily complicated.

[Vishu]

I agree to James, Sanjeev and Patrick...

if you have online JFS, do it on fly. Even no need to unmount it.

Thanks