[DRBD-user] Xen, live migration and fencing with pacemaker

infernix infernix at infernix.net
Mon Nov 30 13:41:22 CET 2009


Hi,

I've been looking at the DRBD user guide, Xen chapter and am confused by 
this part:

"CRM configuration mode. If you are using the Heartbeat cluster manager 
(in CRM configuration mode), you may configure a Xen domU as a Heartbeat 
resource, and automate resource failover. To do so, use the Xen OCF 
resource agent. If you are using the drbd Xen device type described in 
this chapter, you will not need to configure any separate drbd resource 
for use by the Xen cluster resource. Instead, the block-drbd  helper 
script will do all the necessary resource transitions for you."

Thats all fine and dandy and it seems to work, until fencing comes into 
play. I've tried to use the crm-fence-peer.sh and unfence-peer.sh 
scripts, but they fail to execute succesfully because they look at the 
CIB and try to find the master for a given drbd resource. Since I don't 
have to add these to CRM, but the (un)fence scripts do require them to 
work correctly, I get errors like:

crm-fence-peer.sh[5804]: invoked for r0
cibadmin: [5808]: info: Invoked: cibadmin -Ql
crm-fence-peer.sh[5804]: WARNING drbd-fencing could not determine the 
master id of drbd resource r0
kernel: block drbd0: helper command: /sbin/drbdadm fence-peer minor-0 
exit code 1 (0x100)
kernel: block drbd0: fence-peer helper broken, returned 1
kernel: block drbd0: State change failed: Refusing to be Primary while 
peer is not outdated

This obviously isn't what I'd like to happen :)

So the question is, what's the right way to do fencing in a xen 
live-migrating cluster? And could the Xen chapter get updated with this 
info?

drbd.conf: http://pastebin.ca/1693834
pacemaker cib: 
http://developerbugs.linux-foundation.org/attachment.cgi?id=1529

Thanks!

Regards,

infernix


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