topic Re: Query regarding lvreduce on HP-UX 11.23 in Operating System - HP-UX

Query regarding lvreduce on HP-UX 11.23

sanwin — Fri, 31 Dec 2010 07:59:15 GMT

Hi All,
On a production system running HP-UX 11.23 and with no online JFS, can we reduce the size of the lv online.

Someone has increased the size of the currently mounted lv. But not able to extend filesystem as it is not online JFS.

So i want to reduce the added space on that LV.

I am little scared as it is production. I heard defragmentation needs to be done before lvreduce.

Please help me with your comments regarding how to do lvreduce without affecting the production.

Thanks!!

Regards,
Sanwin.

Re: Query regarding lvreduce on HP-UX 11.23

Shibin_2 — Fri, 31 Dec 2010 08:05:42 GMT

As long as you haven't re-organised your file system ( i.e. fsadm or extendfs ), you can do lvreduce to make it back as original.

Re: Query regarding lvreduce on HP-UX 11.23

sanwin — Fri, 31 Dec 2010 09:40:15 GMT

Thanks Shibin!!

Re: Query regarding lvreduce on HP-UX 11.23

sanwin — Fri, 31 Dec 2010 10:47:33 GMT

Hi,
When i run lvreduce i am getting this message.

What does this mean?

Whether it will remove the old data which was there before expanding the LV.

PLease help me.

When a logical volume is reduced useful data might get lost;
do you really want the command to proceed (y/n) :

Re: Query regarding lvreduce on HP-UX 11.23

rariasn — Fri, 31 Dec 2010 11:10:13 GMT

Hi Sanwin:

LVM does not store any information about which physical extents within a logical volume contain useful data; therefore, reducing the space allocated to a logical volume without doing a prior backup of the data could lead to the loss of useful data. The lvreduce command on a logical volume containing a file system of greater length than the size being reduced to will cause data corruption.

man lvreduce

rgs,

Re: Query regarding lvreduce on HP-UX 11.23

sanwin — Fri, 31 Dec 2010 14:15:26 GMT

Thanks!! Actually the data is of size 10 Gb.
Current lv size is 20 Gb and i am trying to reduce to 10 GB.

My doubt was whether it will reduce the unused space or there will be issues with data?

Thanks!!

Re: Query regarding lvreduce on HP-UX 11.23

N,Vipin — Fri, 31 Dec 2010 14:46:19 GMT

I would like to know what is the size in bdf output.

Re: Query regarding lvreduce on HP-UX 11.23

Doug O'Leary — Fri, 31 Dec 2010 15:13:44 GMT

Hey;

Lvreduce will reduce the lv from the end of the chain. Since the filesystem was never extended across the newly added extents, you should be fine.

You're in a position that's about as safe as it's going to get to run that command. The warning messages don't do anything for the comfort factor, though; I'll freely admit.

Doug

Re: Query regarding lvreduce on HP-UX 11.23

sanwin — Fri, 31 Dec 2010 15:17:12 GMT

Thanks Doug!! Currently it is mounted with 10 Gb.

I will try then.

Thanks!!

Regards,
Sanwin

Re: Query regarding lvreduce on HP-UX 11.23

N,Vipin — Fri, 31 Dec 2010 15:26:59 GMT

100% agree with Mr Doug.

Re: Query regarding lvreduce on HP-UX 11.23

Emil Velez — Sat, 01 Jan 2011 03:36:02 GMT

make sure the file system is mounted and it should not kill any data. For example

1. LV was 10 GB
2. you extended the LV to 20 GB
3. You do not extend the filesystem
4. reduce the LV to 10.01 GB while it is mouned that way it will not let you reduce the LV smaller than the FS structure that is mounted.