ORACLE RAC ASM disk question

02-11-2008

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ORACLE RAC ASM disk question

Perhaps someone here has some experience with this.
machine os RHE 4 6
oracle 10g RAC
disk is SAN attached clariion.

I have presented new disks to the host, so the machine sees all needed LUNS. powermt shows them, they are labeled and i have fdisk'd them.
They are visible across all RAC hosts.

We cannot seem to get ASM to recognize them. Thoughts?

Last edited by Eronysis; 02-18-2008 at 01:50 PM..

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02-15-2008

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We had some strange problems on our Sun boxes when using StorageTek FC SAN disks and Oracle 10g ASM (raw devices)

We had to make the solaris slices (partitions) start at block 1 (and not block 0) of the disk for them to show in ASM..
I have no idea why

I dont know if this helps at all

Cheers!

s93366

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02-16-2008

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Same problem here, and we've solved in the same manner s93366's said!

And of course, have a look at the raw device file permissions also. RHEL has the bad habit to reset raw devices file permissions at every boot of the server.

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02-17-2008

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wow I just tought this was some strange flux on Solaris boxes.
Any Oracle experts have any ideas to why it behaves in this manner?

It wasnt that easy to figure out

/s93366

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02-18-2008

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There's an oracle metalink note (368840.1) explaining that, but isn't very detailed:

Quote:

"... information for the partitions and other data is contained in a special structure stored within the first 512 bytes of the disk, on the first cylinders. This structure is called VTOC (Volume Table of Contents). Actions like re-writting the VTOC will cause loosing the disk.

The output displayed above is a typical configuration, where slice 0 was formatted using the hole disk. When using ASM and during the disk discovery, the previous configuration is the cause for missing disks or disks not been discovered. The reason seems to be that having partitions that start at cylinder 0, the complete partition is interpreted as the VTOC area which is not used as a regular partition of the disk."

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