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Oracle RAC with ASM and without ASM

Occasional Advisor

Oracle RAC with ASM and without ASM

we planing to install RAC 11g instance active/active . and we are using SAN storage RAID 10.

I know ASM is nice feature . but it need more maintenance in future . This is what I see
it from Manual and training . for patching ..... because it maintain as instance.

why I do need ASM since I have SAN and I can control mirroring ...etc

I need sold answer here ?? why I need to use this feature that already can be covered using another facility like SAN.


We are running HP-UX 11 v3 .

I hope I find answer here regarding this feature


Re: Oracle RAC with ASM and without ASM

Well yes a SAN can do mirroring etc... but there are times when you need more functions (not all SAN storage devices are created equal after all)

In those situations we use a volume manager like LVM or VxVM. Oracle decided they wanted a special volume manager just for their database so produced ASM.

You have some very important decisions to make on whether to use ASM or not...

Remember in Oracle RAC configurations you need to have shared concurrent access to the same data - the _only_ ways to achieve that right now are:

- raw disks (i.e. oracle reads/writes direct to /dev/rdisk/diskN etc...)

- raw volumes from a volume manager such as LVM or VxVM (i.e. oracle reads/writes direct to /dev/vg01/rlvol1 or /dev/vx/rdsk/vol1 etc...)

- Using ASM as the volume manager between Oracle and the raw disk

- In some cases it can make sense to use ASM over LVM or VxVM

- Using a Cluster Filesystem (CFS) such as Veritas's ClusterFilesystem

On HP-UX, if you are planning to use Oracle clusterware rather than Serviceguard Extension for RAC for clustering then you pretty much have to use ASM or straight raw disks.

And from the next version of the database (I think 12g if they stick with the same naming scheme), Oracle are planning to deprecate raw disks and volumes. At that point the choices for deploying RAC with just clusterware will be ASM. for Serviceguard extension for RAC you would still be able to do ASM over LVM/VxVM or a Cluster Filesystem. However as Cluster Filesystems cost more $$$ I think you can safely say that most folks will end up using ASM for RAC.

Now I don't like this state of affairs - in fact I think it stinks and has more to do with Oracle trying to take wallet share and lock-in customers than it has to do with real value (in my experience DBAs make terrible storage adminsitrators and don't really want to get involved in all that LUN stuff - but with ASM they have no choice), but that's the way its going and will continue to go.

Anyway - lots of material on ASM from Oracle here:


Be careful about what you read on ASM in 11gR2 - I'm not sure all of the functionality discussed at oracle.com will necessarily make it into the HP-UX release...

All my own opinions , not my employers etc...




Occasional Advisor

Re: Oracle RAC with ASM and without ASM

Hi Duncan ,

if we planning deploy it with HP-UX what choices ?

if we are choosing LVM from HP-UX is it better rather than ASM.

any way I am working as DBA . I think management of ASM will make alot of trouble because we need to know much more for LUNs, like you said.

we are using also Clusterware and serviceguard as well.

what other choice can be used rather than ASM form HP-UX point of view.??

Re: Oracle RAC with ASM and without ASM

If you are using Serviceguard, there are a few good white papers discussing your options here:







Emil Velez
Honored Contributor

Re: Oracle RAC with ASM and without ASM

Oracle RAC implementation on HPUX works fine with

Serviceguard Extension for RAC
Cluster File system for RAC storage

The clusterfile system uses cluster VXVM and mounts the same filesystems on all the cluster nodes for RAC. Good solution.
Occasional Advisor

Re: Oracle RAC with ASM and without ASM


this is good . the soultion will delivered by vendor HPUX itanium with out ServiseGurd

it will depened on Clusterware for Oracle using ASM.

in this case what other options can we used in this case from HP??

By the way Thanks all for your help