Re: How to backup ASM?

On 02 Dec 2005 09:57:28 GMT, albe_at_culturall-dot-com.no-spam.invalid (Laurenz Albe) wrote:

>I recently experimented with ASM and ran into a problem that neither
>the manuals nor a web search could solve for me.
>
>My problem is: How do I backup the ASM instance? There has to be some
>metadata in an ASM instance, since the SPFILE only contains the names
>of the disk groups. There should be a way to backup the metadata,
>right?
>
>I created an ASM instance and, in a database that already existed, I
>created an ASM tablespace (this is version 10.1.0.3).
>
>I created a table with some data in that tablespace, then I made a
>datafile copy backup with RMAN.
>
>Then I went ahead and zeroed the ASM disks with
>dd if=/dev/zero of=/dev/whatever
>
>As was to be expected, the database complained.
>I shutdown the database, started in in mount mode, took the datafile
>offline and restored and recovered it with RMAN. The database was
>happy
>after that.
>
>The ASM instance, however, is corrupted. I don't have the system at
>hand,
>but when I start it it complains that it doesn't have a quorum for the
>disk group (I don't have the system any more, but I believe it was
>ORA-15063).
>
>How do you prevent such a situation?
>
>Thanks for any suggestions,
>Laurenz Albe
>

Hi Laurenz,

You need to restore the disk(group) info. Which is the metadata created when you issue commands like
"Create/alter/drop diskgroup <bla>-<bla>"

But you need a backup to restore, of course. Which can be carried out in 2 ways :

1. Keep track of all commands ever issued against the ASM instance (probably few ever), especially those altering/creating/dropping diskgroups and store that info in a text file.
2. Dump the contents of the V$ASM* views of the ASM-instance Regularly. Especially, you would want to track content of the views V$ASM_DISK and V$ASM_DISKGROUP.
   • Kenneth Koenraadt