Re: [CentOS] resize LVM (ext3)

On Wed, Oct 29, 2008 at 12:58:32PM +0100, David Hláčik wrote: <snip>

1. How can i be sure that i will shrink ext3 to exact size 80GB and that

dev=/dev/system/home resize2fs $dev 80G

Then, to be sure of the real size: blks=$(tune2fs -l $dev | awk -F: '/Block size/ { print $2/512 }') fssize=$(tune2fs -l $dev | awk -v bs=$blks -F: '/Block count/{print $2*bs}')

Now, $fssize has the complete size in bytes. Verify it: echo $fssize

Now, for lvresize: lvresize -L 80G system/home

Verify that the printed target size matches the wanted value.

3. Or can i just use lvreduce and my ext3 will shrink automatically?

NO! lvreduce doesn't care about what's inside, and will happily lose data.

4. Do i need to umount system/home when resizing?

Yes, and you must do a full fsck also:

e2fsck -f /dev/system/home

Regards, Luciano Rocha