On Sat, January 6, 2007 3:20 am, Johnny Hughes wrote: > On Fri, 2007-01-05 at 19:04 -0500, Paul wrote: >> 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! >> > > Good job ... first thing to understand (at least as I understand it :P) > is that you will only be able to create a snapshot that is 6GB or > smaller. > > So, as long as the used space on the LVs you take snapshots of are < 6GB > will be OK, otherwise you will have problems. > > My understanding is that you need free space that is going to be at > least as large as the "used space" on the "LARGEST" LV that you are > going to create a snapshot for. (At least that is how I currently setup > my VGs and LVs where snapshots are involved). Well, I know I have way more than enough space, but it was my understanding that you can have way less space than is actually used, cause the space just tracks changes. I used to use "fssnap" in Solaris allot and that doesn't take any space at all, cause it's just some kind of tracking info, I think that is at least what I can compare it to in my mind. So, even though I am using 6gigs worth, I can do a snapshot with like probably 500megs easy. I think anyhow.