[Pacemaker] Using SCSI reservations with Pacemaker

[Max Williams]

Hi All,
I am setting up a new cluster using RHEL6, pacemaker-1.1.2-7 and corosync-1.2.3-21. So far everything works as expected including fencing via Dell DRAC cards but I wish to use SCSI reservations, preferably SCSI-3 persistent reservations but I am not sure on the configuration or even what to install to achieve this.

I've installed the Redhat fence-agents package which includes fence_scsi. fence_scsi uses sg_persist (from the sg3_utils package) which is SCSI-3 only. Now, if you check the Redhat documentation:
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Configuration_Example_-_Fence_Devices/SCSI_requirements.html
It states the SCSI fencing requires LVM2 cluster volumes so I install the lvm2-cluster package (which depends on openais, modcluster and cman!) but cannot start clvmd:
[root at cluster1 ~]# /etc/init.d/clvmd start
Starting clvmd: clvmd could not connect to cluster manager
[root at cluster1 ~]# tail -1 /var/log/messages
May  5 17:16:32 cluster1 clvmd: Can't open cluster manager socket: No such file or directory

So I assume clvmd is trying to connect to cman/modcluster/rgmanager or something and that I am going about this totally the wrong way. I guess I need an OCF resource agent for SCSI-3 persistent reservations, correct?

I did see this message:
http://www.gossamer-threads.com/lists/linuxha/dev/71556
Anyone used this RA in a production system?

Although I have fencing via the DRAC cards, I don't feel super confident about this method when using a shared LUN. Do others feel the same?

How have other people approached the problem of ensuring data consistency when using shared storage with Pacemaker/Corosync? SFEX?

Thanks in advance,
Max Williams

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