This content has been marked as final. Show 9 replies
There is no rebalancing happen for adding/deleting/modifying a datafile. (if you want to verify then check in v$asm_operation view, at the time of adding/deleting/modifying a datafile), you will come to know.
Rebalancing is purely feature of ASM and work at Disk Level ONLY.
I hope this helps you :)
938741 wrote:About Files over ASM (BALANCE):
Hi ASM Team,
I ts know that rebalancing occurs when ver a disk is added or removed ora some physical action is performed..its ok
But my question here is is there any other operation like adding/deleting/modifying a datafile that will lead to rebalancing??
The contents of Oracle ASM files are stored in a disk group as a set, or collection, of extents that are stored on individual disks within disk groups. Each extent resides on an individual disk.
Oracle ASM data distribution policy is capacity-based. So, when you create/resize/delete a datafile Oracle ASM will create/delete a extent in each ASMDISK of that Diskgroup to maintain data distribution equal in all ASMDISK.
This operation is not rebalance, but it's data distribution or only "BALANCE"
About Rebalance Operation (REBALANCE):
Rebalance occurs when something changes characteristic of a balanced Diskgroup unbalancing it, so you will need REBALANCE it.
Operation that cause UNBALANCE of ASMDISK are addition/removal/resize of ASMDIKS in ASM Diskgroup or change of attribute CONTENT.TYPE (188.8.131.52 only)
Rebalance is different of Balance, don't confuse it.
Thanks Levi for detailed explaination,
So Conclusion could be,
*ASM Rebalance feature is more of Striping of data (could be called distribution) across all disks when add/delete/resize takes place.
* While adding/deleting/resizing datafile seen ARB0-ARB9 Processes idle and doesn't perform any rebalance operation at disk level. (instead it happen at extent level)
Correct me if I'm wrong...
Edited by: Hungry DBA on Mar 15, 2013 10:33 PM
938741 wrote:Not to be rude -well yes, I will be rude... if you were to actually read the documentation you would see that the question has been asked and answered and I doubt Aman knows more about it than what has been said. Some of us here have been using ASM since it was introduced many years ago. If you don't like the answers, then it would behoove you to research the answer for yourself... A simple google search turns up a LOT of hits on the subject. It you can't use google, then you may need to find another line of work.
Will wait for Hussein,Aman to comment on this to be sure on this.....
Thanks for your help...
Now, there are several Oracle Press books on the subject, one that would shed more light was written by some of the developers called "Automatic Storage Management - Under-the-Hood & Practical Deployment Guide" by Nitin Vengurlekar, Murali Vallath and Rich Long with a forward by Bill Bridge, the ASM Architect.