Oracle RAC/Shared Volume Group and I/O

[Pedro Cirne]

Hi,

We have a cluster with Oracle RAC running with shared volume groups for raw devices:

VG Name /dev/vg02
VG Write Access read/write
VG Status available, shared, server


and

VG Name /dev/vg02
VG Write Access read/write
VG Status available, shared, client


My simple question is: When the node that has the volume group shared as "client" request I/O, the I/O is made directly to the disks or goes through the "interconnect" and is made on the node where the shared volume group is "server"?

Thank you very much :)

[Duncan Edmonstone]

I'm pretty sure that this client/server relationship just relates to LVM metatdata (e.g. whther any extents are stale and need remirroring etc.) Actual user IO goes direct to the disk from the local host (not over the interconnect) -otherwise performance would be pretty poor!

HTH

Duncan

[Steven E. Protter]

Shalom,

The I/O is direct with Oracle RAC and HP-UX LVM raw disk areas. asynchronous I/O needs to be set up on both systems for Oracle RAC to function correctly.

Also note, that if required OS patches are not installed before Oracle, this functionality may not work correctly.

SEP

[Pedro Cirne]

Hi,

Thank you both for you answers.

I'm not having a problem, I just wanted to check.

I've been told that in a Sun Cluster when you have a disk as "global device" the I/O requested on the "secondary" node is made on the node acting as "primary".

All the I/O from the "secondary" node goes through the interconnects to the node acting as "primary" and then to the disks....do you know if this is true?

Thank you all.

[Duncan Edmonstone]

Yes, SunCluster works as you describe, but SGeRAC and SLVM does not.

HTH

Duncan

[Pedro Cirne]

Thank you for the feedback.

[Pedro Cirne]

Thank you again, closing this thread.