12c Database : ASM Enhancements : Estimate the work for adding/deleting disks

Before 12C,we can only come know about estimate time of disk add/drop like expensive operation at diskgroup level. So,We could not predict how much time this will take in before hand .

In 12c ASM, a more detailed and more accurate work plan is created at the beginning of each rebalance operation.

In addition, DBAs can separately generate and view the work plan before performing a rebalance operation.

This allows DBA to better plan and execute various changes such as adding storage, removing storage or moving between different storage systems.

DBAs can generate the work plan using the ESTIMATE WORK command.

Querying from V$ASM_ESTIMATE view give an idea of required time of that operation based on current workload on the system. So,in while planning such operation ,DBAs needs to take consideration of system load and without running the original operation can make approximate
estimation of their operation at ASM level.

If you want to drop a disk from a diskgroup and if you specify wrong disk name ,then this will estimation will fail. Need to give proper disk name.

SQL> explain work set statement_id='drop_test_failgroup_0000' for alter diskgroup test_failgroup drop disk test_failgroup_0000;
Explained.

SQL> select est_work from v$asm_estimate where statement_id='drop_test_failgroup_0000';
EST_WORK
----------
42

-Thanks

Geek DBA