[CentOS] Freeing pv space for snapshots
Paul
unix at bikesn4x4s.com
Sat Jan 6 00:04:46 UTC 2007
On Thu, January 4, 2007 11:40 pm, Alvin Chang wrote:
> On 05/01/07, Aleksandar Milivojevic <alex at 8-p.ca> wrote:
>> I've used it, and it works correctly (and it is available in CentOS
>> 4.4). It shrinks file system as it should. The only things Paul should
>> be careful is to first shrink file system, than logical volume and to
>> correctly calculate file system size and by how many extents he can
>> shrink logical volume. If he shrinks logical volume too much, he might
>> end up loosing data. Running fsck in non-destructive mode (fsck -N)
>> and/or attempting to mount file system read-only after he shrinks
>> logical volume might be a good idea to test all is OK.
> A little technique you can use is:
> 1. shrink the file system to the size slightly less than what you really
> want
> 2. reduce LV to the size that is what you really want
> 3. expand the file system to the size of the LV (usually the resize
> program can be told to expand the file system to maximum available
> space automatically on the LV.)
You guys are great! Thanks. It was a breeze! I really have fun learning
more and more. I feel like an LVM expert now. Here's the steps I took:
First my lv was like 38G, and I wanted to make it about 32G in the end. I
know that should be way more than enough. I also did a dd to an image
file on a secondary drive for a precaution (always have a failsafe
recovery!)
1. booted up on CentOS 4.4 Live CD. -When I booted up on it, I told it
to boot nonet to not bring up the interfaces, but it did anyhow. I did a
"ifconfig eht0 down" to do a shut on it. Anyhow, out of all the LiveCD's
I have tried, I do like the Centos the best!
2. e2fsck -fv /dev/VolGroup00/LogVol00
3. resize2fs -p /dev/VolGroup00/LogVol00 30G
4. lvresize -L 32G /dev/VolGroup00/LogVol00
5. resize2fs -p /dev/VolGroup00/LogVol00 (size defaults to lv size)
Now I have my free PV space!
# pvdisplay
--- Physical volume ---
PV Name /dev/hda2
VG Name VolGroup00
PV Size 38.22 GB / not usable 0
Allocatable yes
PE Size (KByte) 32768
Total PE 1223
Free PE 143
Allocated PE 1080
PV UUID cQCke5-zi9o-xhOW-HlR5-M46g-VbHC-99Csch
Now I am on to learning how to do a full backup with snapshots!
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