Disk Array Migration for ASM Databases

This blog identifies the DBA steps required to migrate databases from one disk array to another.
Identify the ASM diskgroups and their disk (LUN) sizes
Login to the ASM instance and identify the LUNs allocated to server.

For 11g ASM:


For 10g ASM:


You may discard LUNs with group number 0, as they are not part of any diskgroup. Request Sysadmin team to provision the new LUNs to the server, same LUN size or total of multiple LUNs in the group is equal or more to what is allocated to the group. 

 To find out what is allocated and free in each diskgroup, you may use:

Once LUNs are provisioned by Unix team, use OEM or SQL to add the LUNs to respective diskgroups [existing diskgroup]. NO outage required for this step. Remember to login to 11g ASM using the SYSASM privilege, for 10g login using SYSDBA privilege.


To find out which LUNs are available to add, you may use SQL:

{for 10g ASM, please substitute os_mb with total_mb}
Then, go ahead and drop the old LUNs. No need to wait for the add operation to complete.

The name of the LUN can be found by querying the V$ASM_DISK…


Keep the rebalance power low, so that the migration activity does not impact database performance.

You may check the progress of rebalance periodically using V$ASM_OPERATION, once no rows are in this view, you may advice SYSADMIN team to pull out the old LUNs from the server. V$ASM_OPERATION also shows the work so far completed and how long it will take to complete the work.

Leave a Reply

%d bloggers like this: