[DRBD-user] Using XenServer HA with DRBD

Adam Gandelman adam.gandelman at linbit.com
Mon Jul 26 18:59:57 CEST 2010

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On 07/26/2010 05:23 AM, Robert @ GMail wrote:
> @: Thomas Stinner <thomas.stinner at schuechen.de>
> Subject: [DRBD-user] Using XenServer HA with DRBD
> I'm quite sure you know that i.e. xenserver free has got many features
> disabled, here it is the comparison table
> http://www.citrix.com/English/ps2/products/subfeature.asp?contentID=2300456
> if you are using the free edition, you must manage to install some
> cluster framework, i.e. heartbeat+pacemaker. I'm still searching for
> some documentation about implementing it on xenserver.
> If you find it... please share the links.
> R.

For xenserver setups, you may configure DRBD in dual primary mode and
import that device as a shared SR into XenServer.  You'll still need
some other shared storage to be used for XenServer's HA extension.  I
believe the HA extension prefers iSCSI for this.  You can configure an
additional, small DRBD resource and export it via iSCSI to be used for
heartbeating, quorom, etc but it will need to be managed on its own
using heartbeat/Pacemaker at the dom0 level.  Ideally, pacemaker will
also be managing the state of the DRBD resource.

In most cases, DRBD imported into XenServer as a raw SR will result in a
broken SR after failover.  It is not transparent and requires someone to
go in and repair the SR after failover.  An alternative would be to use
a single primary DRBD resource, exported via iSCSI and managed at dom0
by pacemaker+heartbeat.  Import this iSCSI LUN as the shared SR and
failover of storage can happen between dom0s totally transparent to your

XenServer is essentially CentOS so with some effort it is not difficult
to get things like heartbeat and Pacemaker installed and running. Then,
check out any number of documents available covering HA DRBD + iSCSI or
consult LINBIT for professional support. :)

Side note: You may want to check out Xen Cloud Platform
(http://www.xen.org/products/cloudxen.html) --  it is essentially
XenServer open-sourced.  Native DRBD support is on the roadmap and I
know there is someone currently working to implement this. 

: Adam Gandelman
: LINBIT | Your Way to High Availability
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