Is it possible to move a disk from a diskgroup to another one ?

Question

Hi,
I did not find the answer so here is my question :
My environment is Oracle 11g (11.1.0.6.0) database on OEL5U3.
The system contains 2 diskgroups (DATA and RECOVERY) which respectively contains 1 disk (DATA contains VOL1 and RECOVERY contains VOL2). VOL1 and VOL2 are the ASM disk names assigned by oracleasm to /dev/dpdb1 and /dev/dpdc1
SQL> select name,GROUP_NUMBER,TYPE FROM V$ASM_DISKGROUP;
NAME GROUP_NUMBER TYPE
DATA 1 EXTERN
RECOVERY 2 EXTERN
SQL> SELECT NAME,PATH FROM V$ASM_DISK;
NAME PATH
DATA_0000 /dev/oracleasm/disks/VOL1
RECOVERY_0000 /dev/oracleasm/disks/VOL2
My ultimate goal would be to use a snapshot-copy of /dev/dpdb1 (VOL1) to create a new diskgroup on the same server.
Let's say that my snapshot-copy of LUN /dev/dpdb is seen as /dev/dpdh:
# /etc/init.d/oracleasm querydisk /dev/dpdh1
Device "/dev/dpdh1" is marked an ASM disk with the label "VOL1" <-- the label on the disk is of course VOL1
# /usr/sbin/oracleasm renamedisk -f /dev/dpdh1 VOL3 <-- update of the label
Writing disk header: done
Instantiating disk "VOL3": done
# /etc/init.d/oracleasm listdisks
VOL1
VOL2
VOL3 <-- the new disk is now listed
Then I try to create the new diskgroup:
SQL> create diskgroup TIMEVIEW external redundancy disk '/dev/oracleasm/disks/VOL3';
ERROR at line 1:
ORA-15018: diskgroup cannot be created
ORA-15033: disk '/dev/oracleasm/disks/VOL3' belongs to diskgroup "DATA"
The same command with force option:
SQL> create diskgroup TIMEVIEW external redundancy disk '/dev/oracleasm/disks/VOL3' force;
Diskgroup created.
The issue here is that the newly created diskgroup is empty ! it does not contains original files. Did I miss something ?
Edited by: user11239258 on 21 oct. 2009 01:06
Edited by: user11239258 on 21 oct. 2009 01:07

Answer 1

The md_backup and md_restore are finally not helpful in my case. it doesn't change the fact that ASM metadata are written in the disk header.
I could try to update the header with dd and hexadecimal editor but I'm looking for a decent option here.
The only solution I've found is to shut down ASM instance, move the block special file /dev/oracleasm/disks/VOL1 pointing to the original disk to a safe location, create a new block special file using mknod to point on my disk (the snapshot), restart ASM instance and use asmcmd cp command to retrieve needed files.
Conclusion : snapshot backup is fast but recovery based on snapshot is slow dealing with ASM.
RFE : A command similar to vgimport would be nice to have with ASM disks, it would allow the creation of new diskgroup without losing the content of an ASM disk or a group of disk.