I blogged yesterday about Oracle over NFS performance and NFS protocol for Oracle. In the post I referenced a recent thead on comp.databases.oracle.server where Oracle over NFS performance was brought into question by a list participant. I addressed that in yesterday’s blog entry. The same individual that questioned Oracle NFS performance also called for proof that Oracle supports using large files in an NFS mount as “disks” in an ASM disk group. I didn’t care to post the reply in c.d.o.s because I’m afraid only about 42 people would ever see the information.
Using ASM on NAS (NFS)
I’ve blogged before about how I think that is a generally odd idea, but there may be cases where it is desirable to do so. In fact, it would be required for RAC on Standard Edition. The point is that Oracle does support it. I find it odd actually that I have to provide a reference as evidence that such a technology combination is supported. No matter, here is the reference:
If you have a certified NAS storage device, you can create zero-padded files in an NFS mounted directory and use those files as disk devices in an Automatic Storage Management disk group. To create these files, follow these steps:
To use files as disk devices in an Automatic Storage Management disk group, the files must be on an NFS mounted file system. You cannot use files on local file systems.
A Dirty Little Trick
If you want to play with ASM, there is an undocumented initialization parameter that enables the server to use ASM with normal filesystem files. The parameter is called _asm_allow_only_raw_disks. Setting it to FALSE allows one to test ASM using zero-filled files in any normal filesystem. And, no, it is not supported in production.
For more information about ASM on NAS, I recommend: