Multiple PVs in cluster lock VG

[Rudy Williams]

Folks--

I have three PVs as part of the VG that is the cluster lock. Is it possible to include all of the PVs in the cluster configuration file? Is it wise do to thi in case one of the disks/LUNs becomes unavailable?

Also should I include the device files for the PV via the alternate path?

cjw

[Duncan Edmonstone]

No, it is not possible. Cluster lock disks are just single disks in a volume group - you should just pick one disk in your volume group to be the cluster lock disk. You also cannot include the alternate link to the cluster lock disk in the configuration. You should only use a secondary cluster lock disk in very specific configurations as described in the Managaing ServiceGuard Manual - to summarise:

'The use of a second cluster-lock disk is recommended when there is no third power circuit to power the "clustered" disks, including the cluster-lock disk. This may occur when each host has a set of disks in it's own rack. This is not as highly available as a 3rd power circuit, but neither is the loss of a sole cluster-lock disk when a cluster reformation is triggered by loss of cluster heartbeat transmission. When using two cluster lock disks, both disks MUST be powered by separate supplies.'

Remember cluster lock disks only come into play *after* other failures have occurred, and then only to prevent data corruption. If your cluster is designed correctly the cluster lock disk is the last resort anyway.

HTH

Duncan

[Jeff Schussele]

Hi cjw,

No, it's not wise & not allowed anyway, I don't think.

The way the lock works is two-fold. The Lock VG AND the lock PV have to both be unavailable. If you lost them both, you've probably got bigger trouble than a quorum deadlock.

Just define the LOCK VG & one of that VG's PVs as the LOCK PV and that's all you need.

My $0.02,
Jeff

[melvyn burnard]

It does not matter how many disks you have in the VG for the Cluster lock, you can only point to one disk.
You cannot mirror the Cluster Lock area, and unless you have specific circumstances, you should not have a second lock defined.
You can also not use the Alternate link for a cluster lock disk.
Have you investigtaed maybe using the new Quorum Server software, rather than a cluster lock disc?
Note that if you have to use the Lock disc, the VG does not have to be activated, at all, you just need to have the disc available.

[Sridhar Bhaskarla]

Hi Cjw,

The answers to both your questions is "no". When HP says "recommended", it will be difficult to get support later though.

Except from the serviceGuard manaul.

//
You can choose between two cluster lock options -- a single or dual cluster lock -- based on the kind of high availability configuration you are building. A single cluster lock is recommended where possible. With both single and dual locks, however, it is important that the cluster lock disk be available even if one node loses power; thus, the choice of a lock configuration depends partly on the number of power circuits available. Regardless of your choice, all nodes in the cluster must have access to the cluster lock to maintain high availability.//

About the alternate paths, again HP does not recommend using the alternate link either.

-Sri

[Farid Feknous]

Hi Cjw

As Melveyn Said If you have a new version of SG and if you have an unused server(not part of the cluster) you can instead of using Lock disk to use the Quorun Server softwrae and it's free.

Regards.