Re: XFS on top RAID10 with odd drives count and 2 near copies

On 12/02/2012 21:16, CoolCold wrote:

First of all, Stan, thanks for such detailed answer, I greatly appreciate this!

On Sat, Feb 11, 2012 at 8:05 AM, Stan Hoeppner[off-list ref]  wrote:

quoted

On 2/10/2012 9:17 AM, CoolCold wrote:

quoted

I've got server with 7 SATA drives ( Hetzner's XS13 to be precise )
and created mdadm's raid10 with two near copies, then put LVM on it.
Now I'm planning to create xfs filesystem, but a bit confused about
stripe width/stripe unit values.

Why use LVM at all?  Snapshots?  The XS13 has no option for more drives
so it can't be for expansion flexibility.  If you don't 'need' LVM don't
use it.  It unnecessarily complicates your setup and can degrade
performance.

There are several reasons for this - 1) I've made decision to use LMV
for all "data" volumes (those are except /, /boot, /home , etc)  2)
there will be mysql database which will need backups with snapshots 3)
I often have several ( 0-3 ) virtual environments (OpenVZ based) which
are living on ext3/ext4 (because of extensive metadata updates on xfs
makes it the whole machine slow) filesystem and different LV because
of this.

This is a bit off-topic, but do you know of any way to get OpenVZ running on a kernel newer than 2.6.32?  One important feature in 2.6.33 is mergeable LVM snapshots, which would be particularly useful for OpenVZ, such as when updating, upgrading or otherwise changing a virtual machine.  With mergeable snapshots you could take a snapshot, apply the changes to the snapshot, and if it works you merge them back into the main logical partition.

mvh.,

David