Re: [Xen-users] Server purchase pointers

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

On Thu, Feb 23, 2012 at 10:06 PM, Bart Coninckx
<bart.coninckx@xxxxxxxxxx> wrote:
> On 02/23/12 10:41, Fajar A. Nugraha wrote:
>>
>> On Thu, Feb 23, 2012 at 4:28 PM, Bart Coninckx<bart.coninckx@xxxxxxxxxx>

>>> I'm planning to make a HA Xen solution based on DRBD and Pacemaker,
>>> mainly
>>> serving as a disaster recovery solution for my customers.
>>
>> have you tried drbd with xen?
>
>
> yes, that's what I'm saying
>

My point is, last time I tried drbd+ocfs2 introduce huge performance
penalty, complexity, and possible data loss. But then again, it was an
active-active setup with no external heartbeat, relying on ocfs2 to
reboot the nodes on split-brain scenario.

If you HAVE tested it, then it's great. As usual, whatever solution
you choose, testing is important.


>
>> It will daily sync their files and mails (rsync, imapsync) and in case of
>> disaster they can access this info by means of web based applications.
>>
>> So I'm basically looking for a budget friendly rack server with good Linux
>> support (will probably be using SLES11).
>> I'd actually suggest you buy a third one, with lots of internal disks,
>> and install whatever OS you're familiar with to act as block storage
>> server. Example: openindiana + nappit + iscsi, SLES + aoe, etc.
>>
>
> That would be a single point of failure, rendering the "frontend" cluster
> kinda useless, except for load balancing. I plan to go for dual primary -
> cost is an issue, so limitation to two servers is key,

"dual primary" and "active-active" is similar, but can be different.
An active-active drbd setup requires protocol C (sync), which (among
others) decrease performance but allow live migration.

An active-standby setup can use async replication, which should be
much better performance-wise. If each node is acting as active for
their own domUs while acting as standby for domUs on the other node,
that can be considered dual primary.

If your definition of dual primary is what I mentioned above, then
yes, drbd would be more appropriate. However if you have live
migration as requirement, then IMHO a third storage server is much
better.

-- 
Fajar

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