ServiceGuard, RAC and LVM.

[Serge Dumont]

Hi all,

I have 2 rp7410, 11i with LVM and SG 11.15
We are still in the planing stage and
I've been reading few documents about RAC.
They all show "raw" LVs in their examples but
I haven't seen any mention that you HAVE to use
a raw LVs.

Do we have to use raw LVs with RAC ?
If so, is there a reason ?

Thanks,
Serge.

[Brian Crabtree · Accepted solution]

Yes. RAC requires the ability to lock individual blocks, so they can be modified. The only way to allow for this is to use a raw LV. With a cooked filesystem, Oracle locks the files fully, so no other instance would be able to lock them. There are supposed to be some file managers out there that allow block locking on a cooked filesystem, however I have not had any experiance with them.

Hope this answers your question.

Thanks,

Brian

[Karthik S S]

Oracle RAC can also be configured on Cluster File System. For this you need to install Veritas CFS (Veritas DB edition) on hp-ux.

Disadvantage on Raw volumes being that one can NOT determine the space utilized by the volume and it is hard to manage (for example extending a Volume)

-Karthik S S

[Karthik S S]

Also, the following cookbook will be very useful for you to setup RAC with LVM.

http://otn.oracle.com/products/oracle9i/htdocs/9iRAChp.html

-Karthik S S

[Serge Dumont]

Thank you Brian and Karthik.
This is exactly what I was looking for.

Serge.