Re: [tlug] Current practices for Linux partioning?

[Christian Horn <chorn@example.com>]

On Fri, Apr 13, 2012 at 07:22:32AM +0200, Attila Kinali wrote:
> On Thu, 12 Apr 2012 14:57:05 +0200
> Francois Cartegnie <fcartegnie@example.com> wrote:
> 
> > What about the "pool" based fs way (btrfs) which will still allow
> > splitting without the drawbacks ?
> 
> 
> I'm following the btrfs development for a few years now, but i don't
> think it's prime time ready yet. There are still too many open issues
> (not having a working fsck yet is one of the biggest). IMHO it will
> take another 4-6 years until btrfs becomes stable enough for general
> use.

We can do this in LVM layer with the new 'thin provisioning' implemen-
tation which is in >=3.2 .  With a decent enough LVM you get then when
creating a volume group a /dev/vgroup/pool and logical volumes can take
from the pool - and put back which is unused.

The new LVM is not yet in Fedora16 but looking forward to have it in 
Fed17 and beeing able to store virtual machines in thin provisioned 
volumes.

Ofcourse, your layers ontop (filesystem, qemu, whatever) have to support
thin provisioning too.


> > Splitting is still useful to compress filesystems (source code) or do
> > efficient snapshot based backups (*), or easily change/revert rootfs.
> 
> Yes, that would help. But, to be honest, how many people would use that?
> How many people even know that such features exists?

Its there for quite some time, for enterprise distros since RHEL6.0 or 6.1 .
Also working on LVM layer: you take a snapshot and perform your upgrade.
You then either decide that the upgrade went well and throw the snapshot
away, or you decide for the rollback and merge the snapshot back into the
original volume.


Christian