Re: [Xen-users] easy high availability storage

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Wed, Nov 25, 2009 at 4:04 PM, Roland Frei <frei@xxxxxxxxxxxx> wrote:
> i want to setup a easy high availability storage system for xen guest os. (1
> pc that run xen and 2 nas for storage)


> XEN
>  xen provides a virtual disc for the guest os. HERE IS THE THING: instead
> that this virtual disc is stored on one drive, is should be STORED ON 2
> NETWORK SHARES. (something like raid1 over lan)


> THE QUESTION
>  is it possible to setup xen so that is uses the 2 network share to store
> the virtual discs ?


Short answer: yes, but if you're new to HA/cluster concept (which,
from your questions, I assume you are) better stay away from it. It's
complicated.

Long answer: there are various approach to this problem, none of them
are one-step-easy-to-install solution.
Here's an approach:
- san exports its storage as iscsi
- server/PC imports iscsi share from both san
- setup raid1 on server using those two iscsi imports
Caveats:
- need to fine-tune iscsi so that when one of the sans are down it
doesn't wait indefinitely
- need to fine-tune/hack Linux RAID so that when the down san comes
back up, it will sync automatically

Here's another approach: If the sans are actually an x86 server with
lots of disk, you can setup drbd + failover cluster on it.
Caveats:
- need to learn drbd and cluster, which IMHO is more complicated than Xen
- in my test setup, sometimes when a drbd node is down, the other one
will reboot as well. Then again it's probably because I use ocfs2 on
top of drbd. YMMV

-- 
Fajar

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users