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VG setup with MC/serviceguard

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Burt Buchen

VG setup with MC/serviceguard

I am not sure I am in the correct forum, this question is not specifically an MC/serviceguard related question, so I opened it under planning. I have an HP9000 rp2405 that has eight external 36gb drives. I intend to put 3 oracle instances on these. I was told for MC/SG each instance should be a separate VG. That is fine but my question is how do I spread a VG across four disks.
I then would like to mirror those disks to the other four I have on that external box. I know I cannot mirror vg only lv's so that should not be a problem but I cannot figure out how to spread three vg across four disks.

It looks like I can only have one vg per disk is this correct? If this is correct the does MC/SG really need to have each oracle database in it's own separate vg?
Any suggestions?

Thanks in advance.

Burt Buchen
Chris Watkins_1
Respected Contributor

Re: VG setup with MC/serviceguard

Limit one VG per disk... correct.
You don't "have" to have each oracle instance as its own
package or on its own VG... but you give up a lot of
ServiceGuard goodness, if you don't do it that way.
(The ability to move only "ONE" of the instances, for instance)
Not without 2 backups and an Ignite image!
A. Clay Stephenson
Acclaimed Contributor

Re: VG setup with MC/serviceguard

A given physical disk can be a member of but one VG but a VG can have N disks. In your case, one VG would have four disks and the other two could have two disks each. This would allow you to mirror all LVOL's on separate physical volumes.

As to whether it make senses to combine 3 Oracle instances into one MC/SG package --- that is a question solely for the designer of the package. For example, if all three instances have to available for a given application to function then it probably makes sense to house them in one package but if some applications can function without requiring the other instances then it makes more sense (and is more robust) to separate them. Even if the instances are separate, you can still have the Oracle binaries in a stationary location, e.g. /opt although my preferred method (at the cost of disk space) is to move binaries (including listener) with the package.

If it ain't broke, I can fix that.
Honored Contributor

Re: VG setup with MC/serviceguard


If you are talking about simple external disks and not a RAIDcabinet then you are right.
One disk can only exist in one volumegroup.

If you like to have all oracle instances in its own package they should have their own VG.

If the all the instances are related and all 3 have to be up for one application then they can be in one package.

To be more flexible I would advise to split it up over 3 packages. When this is done you can choose to run each instance on different nodes in the cluster (load balancing).

Good luck with your configuration.


Tim Nelson
Honored Contributor

Re: VG setup with MC/serviceguard

As you will soon find out. Configuring for Service Guard with conflict with configuring for performance and economical resource allocations. But, if you are service guarding then you have already accepted the expense.

We explored the service guard road long ago and decided that a good SAN configuration and application configs would allow us to manually do what service guard does without the challenges that sercice guard now creates.

Good luck.