Tuesday 1 April 2014

Manually Changing rebalance power in Oracle ASM


 

Manually changing rebalance power on an ongoing ASM rebalance operation     

 
 
A couple of times we remove ASM disks from a diskgroup and found that the rebalance operation will take too long.

This is not a problem when you don't want to disturb online users, the rebalance process only locks for writes 1mb of data at a time, so letting the rebalance to run slowly has no performance impact.

My problem was that I needed to free the disks as fast as possible in order to finish some IO tests within a limited timeframe.

The procedure to change the rebalance power of an ongoing operation is very simple:

alter diskgroup DATADG rebalance power 11;
(Power can be set from 0-11)

After that the rebalance operation will restart with the new set rebalance power.

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