ASM metadata and migrating a database to ASM
June 10, 2009Another ASM entry today covering two discussion points
I had to migrate a database from cooked filesystem to ASM and rather than using a script I used the ‘migrate to ASM’ option in Enterprise Manager. This was the first time and it was an easy point and click task but it did seem to be very slow.
This is documented on OTN at Migrate ASM
The second point covers ASM metdata. If you create a new diskgroup with 5 disks and add the 5 disks as part of the creation using a command similar to
create diskgroup newdg external redundancy disk '/dev/oracle/disk100';
then metadata is written to the disk
If you create the diskgroup adding all 5 disks at the same time
create diskgroup newdg external redundancydisk '/dev/oracle/disk100','/dev/oracle/disk101','/dev/oracle/disk102','/dev/oracle/disk103','/dev/oracle/disk104';
then the metadata is striped across all 5 disks
However if you create the diskgroup with 1 disk and add 4 disks later the metadata is only written to the first disk. I dont see this as a major issue but it does seem a flaw in the functionality
create diskgroup newdg external redundancy disk '/dev/oracle/disk100'; alter diskgroup newdg add disk '/dev/oracle/disk101','/dev/oracle/disk102','/dev/oracle/disk103','/dev/oracle/disk104';
My next entry will also be on ASM and will provide a nice script for backing up metadata
[...] Hallas notes that using Oracle’s EM to migrate a database to ASM is easy, but seems slow, in ASM Metadata and Migrating a Database to ASM. He then goes on to share a coworker’s Script to Backup ASM Metadata. J. Arneil shows how to [...]