Oracle ASM & Cluster File System

[Fernando Espinoza]

Hello:
A customer purchased two rx76xx server with HP-UX 11.31 HA,
aditionally purchased a SMS suite: T8687DB HP-UX v3 HA-OE w/SG CFS for RAC LTU,to be used with Oracle RAC 10.2.0.5
Now the customer wants to use Oracle ASM disk group for RAC y Cluster File System for clusterware.

questions
1.- In the same cluster, Is it posible use ASM with SLVM for one package (RAC) y CFS for another package (clusterware)?
2.- the product T8687DB HP-UX v3 HA-OE w/SG CFS for RAC LTU was the right choice to do this?
3.- Is it posible use ASM without SLVM too?
4.- what about ASM with CFS?

regards

[Alzhy]

1.- In the same cluster, Is it posible use ASM with SLVM for one package (RAC) y CFS for another package (clusterware)?

YES:
ASM ontop of SLVM - /dev/vgsap/asmvol01
(ASM DIskstring -- /dev/vgsap/asm*)

CFS for CLusterware: No Brainer -- Filesystem is active on all nodes.


2.- the product T8687DB HP-UX v3 HA-OE w/SG CFS for RAC LTU was the right choice to do this?

Yes.

3.- Is it posible use ASM without SLVM too?

Yes. You just simply present SAN disks to all the nodes and ASM should pick them up. The issue is how to get consistent names for "ASM Disk string" - so you'd be better off with ASM over i.e. VxVM : /dev/vx/rdsk/sapdg/asmvolNN since the underlying VM of CFS is VxVM anyway (if I am not mistaken)


4.- what about ASM with CFS?
CFS is a FIlesystem - multinode accessible. ASM expects raw disk. Since CFS' underlying Volume Manager is I recall VxVM, you can have your ASM Volumes use VxVM Volumes like: /dev/vx/rdsk/sapdg/asmNN (and your ASM Disk String on all nodes will of course be /dev/vx/rdsk/sapdg/asm*". Note the best practice for ASM on VxVM volume is taht each VOL will need to be on one Disk and not span or stripe over other disks in the DIskgroup.

HTH.

[Steven E. Protter]

Shalom,

In general you want to go with CFS or ASM.

ASM will work by itself. with no other add ins.

CFS will let you run your database on a cooked file system, but the performance and management might be more complex.

ASM give Oracle the disk and lets the DBA's manage everything themselves within the ASM container.

SEP

[Duncan Edmonstone]

So have you asked the customer WHY he wants to do this - seems a crazily complex setup to want if you ask me... although it can work together it makes little sense to do this.

This is like putting half your filesystems on LVM and the other half on VxVM - why not just pick an option and stick with it?

Also given they have purchased the SMS suite which has a significant cost associated with it, you'd think they would want to sweat that investment - I'd disagree with SEP on CFS being more complex - give me a filesystem any day over ASM (most DBAs haven't got a clue when it comes to storage).

HTH

Duncan

[Fernando Espinoza]

Hello
first of all, I want to thank for their answers.
The High Availability Advanced Technology Center says:

1. It is possible to ASM with SLVM for one package (RAC) and CFS for another package (clusterware), but it will complicate the configuration. We recommend CFS (SG SMS CFS RAC) highly because all kinds of files can be stored on a CFS, and administrators have more flexible via the Storage Management features, including Storage Checkpoints, Dynamic Storage Tiers.
2. If you want to use CFS as shared storage for your Serviceguard/SGeRAC deployment of Oracle RAC, yes, you made the right choice.
3. You may use ASM with SLVM on 11i v3. We allow this configuration due to 11i v3â s native multi-pathing capability. But we strongly recommend ASM/SLVM because it provides better resiliency (SLVM I/O drivers have better re-try algorithms), and provides better data integrity (SLVM provides better protection from inadvertent data corruption by nodes inside AND outside of the RAC cluster).
4. ASM with the SG SMS CFS makes no sense, and is not supported. Oracleâ s ACFS is not supported on HP-UX.

regards

[Alzhy]

The HAACT is forgetting something...

ASM over VxVM. VxVM is the volume manager used by CFS -- no?

And I think VxVM has better resiliency, IO Blancing on Tier-1 arrays than LVM/11.31-MSS.

One can also use non Volume Manager'ed raw disks specially if your non-native multipathing software supports custom naming of the disks.

My few cents.


N.