Splitting LVM partition and then mounting

prollocks · 04-07-2010, 03:11 PM

Hi all,

I need to split a logical volume ( only have /boot and lvm partitions on drive)

This new logical volume needs to take up most of the existing space.

I'm just wondering about the sequence of steps to take before I do this.

How do I resize the new/old LVM partitions - and would I need to re-size the underlying fs?

Cheers

mweed · 04-07-2010, 09:03 PM

Not sure what you mean by split, but it sounds like you need to resize the existing LVs and then create a new LV?

become familiar with lvresize, lvcreate, vgdisplay and lvdisplay. Additionally you may need to use fsck and resize2fs (or other filesystem resizing tool)

lvresize will resize the filesystem when resizing the LV by using the -r flag. But it only works under optimal conditions. You will likely need to fsck before resizing.

It is possible to live grow a ext2/3 fs, but not shrink. You can grow and shrink offline.

prollocks · 04-08-2010, 05:06 AM

There is only one LV taking up all the space - would the vgsplit command not be applicable here?

prollocks · 04-08-2010, 06:13 AM

OK looking further into this and you are correct -

I am trying to reclaim space from an existing Logical Volume,

this appears to be a bog standard RH ES install BUT the / is on the LogVol00

How on earth can I resize this (I'm reading I need to unmount Logical volumes and run file-system checks before resizing)??

syg00 · 04-08-2010, 06:22 AM

You've not explained your setup at all. I'll assume one pv, one vg, and one lv.
Get a liveCD or install CD and work from the inside out - shrink the filesystem, then the lv, then the vg if needed. IMHO LVM was designed to add space easily, and shrinking was conveniently ignored. Tools have subsequently been added, but it's all too complicated. I think this is why btrfs will take over - all the tools (will) exist in the filesystem, not yet another psuedo block layer.