Serviceguard lock disk question

[leebob]

Hello,

I currently have a 2 node setup. Does anyone know whether the two nodes have to see the same physical disk in order for the lock disk to work. Could someone explain to me of how the lock disk actually works in terms of preventing a split brain?

Thanks

[Torsten.]

In a situation where the nodes cannot "talk" to each other, each node is trying to get the lock. The node that gets the lock will survive, the other node has to die. For this reason both nodes must be able to "see" the lock device.

[leebob]

So i must create a shared disk on a storage device? There's no way to do this using two local internal disk on each node?

[Torsten.]

The other node cannot access a internal local disk on the server.

If you don't have a shared disk for any reason, consider to use a quorum server.

[leebob]

Thanks for the replies. Would you happen to know whether I should use lock_lun or lock_disk in the config files. I will be using a san device.

Thanks

[g3jza]

Hi,
there are certain restrictions for lock lUN:


-No support for dual Lock LUN (can not be used with extended distance cluster)

-Lock LUN can not hold user data

-4-node maximum cluster size

-Lock LUN can not be shared among clusters,
unlike quorum service

So I'd rather go with Lock disk

[Stephen Doud]

The lock disk must be a member of an LVM VG that is shared/seen by both systems.
The cluster lock VG/pv is only used when exactly half of the nodes in a cluster cannot receive heartbeat communication (on both the dedicated HB and data networks that are identified with HEARTBEAT_IP in the cluster ASCII file) from the other half of the nodes in the cluster. In this event, Serviceguard code on each node attempts to write data to the cluster lock region of the cluster lock PV. If the region is clean, the node that writes the data is allowed to continue cluster operations. The node that finds data there already is forced to TOC/reboot. The node that continues operation eventually reforms the cluster and cleans the cluster lock region for the next usage.

More details about lock VG are available in the 'Managing Serviceguard Ninteenth Edition, April 2011' manual at http://bizsupport1.austin.hp.com/bc/docs/support/SupportManual/c02437444/c02437444.pdf