[Techtalk] Advice on LVM

Eeva Järvinen eevaj at welho.com
Tue Jul 5 12:15:53 UTC 2016

On Tue, Jun 28, 2016 at 11:26:29PM +0000, Poppy Lochridge wrote:

> Previous consultant set up a CentOS system running apache and
> ownCloud. Three logical volumes: one swap, one mounted as the
> ownCloud data folder, one root.

So... root, swap and ownCloud are in the same volume group, and this
VG takes up all available physical space, root is mounted at /,
ownCloud is at /data (or something else)?  You should be able to
resize the volumes, BUT they do need to be unmounted, so if you want
to shrink root, you need to boot from a livecd/usb stick. This link
should be helpful:


Messing about with sizes of volumes isn't quite as dangerous as it
used to be, but yes, this can lead to data loss if you mess something
up (most likely faux pas would be shrinking the volume before
shrinking the filesystem).

I suspect, however, that there is a tried & true method for doing what
you want in an ownCloud-specific way, but as I'm not that familiar
with ownCloud, I can't really comment more on that.

> Staff are SUPER unhappy with the performance of accessing 1TB of
> data via WebDAV, and we're looking at moving their data out to
> another folder which can be shared SMB with their workstations and
> added back into ownCloud via External Storage for cloud-based access
> outside of the office.

What are they using to access the data? Windows PCs, something else?
On the same network, WAN, something else? For a Windows LAN, SMB would
be a good choice, but see also the iSCSI-solutions offered previously
in this thread.

> None of the existing logical volumes have enough capacity to move
> the data to - all of the capacity has been assigned to the ownCloud
> data volume, and I don't want to create an External Storage folder
> there as that seems confusing for the users and future admins.

So you do have unused physical space available? Why not build needed
new logical volumes there, move the data, change mountpoints to point
to new volumes (keep a copy of the old mounting structure), reboot to
see if everything's ok, and if so, nuke the old volumes?

>  (2) Change the mount point on the ownCloud data volume so that it
> mounts further up the folder tree, enabling us to create the
> External Storage folder in that volume without resizing.

So... you have room on the data volume, but need to have the external
storage folder mounted somewhere else in the filesystem? You do
realize you can mount a directory somewhere else with

mount -B /olddir /newdir

(a k a bind mount)? This might be the easiest option for now.


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