topic Re: SAN Disk Group Leveling in Disk Enclosures

SAN Disk Group Leveling

ahlan — Thu, 17 Apr 2008 05:18:29 GMT

Hi all,

This morning, one disk group on my SAN storage performed leveling automatically. There wasn't any disk error that warrant the leveling.

Could anyone enlighten me on why was there a leveling performed, are there any documentation on this and can I find out how long the leveling took.

Thanks

Re: SAN Disk Group Leveling

Jeeshan — Thu, 17 Apr 2008 05:25:39 GMT

Hi Adrian

Which SAN storage?
EMC or HP?

Re: SAN Disk Group Leveling

ahlan — Thu, 17 Apr 2008 05:29:27 GMT

Hi Ahsan,

HP EVA 3000

Re: SAN Disk Group Leveling

Jeeshan — Thu, 17 Apr 2008 05:39:55 GMT

Hi Adrian

The leveling consists on regenerating data if needed and distribute it among all the disks on the diskgroup.
This is a low priority job that is done in the background. Even if the UPS fails and the EVA shuts down unexpectingly, the EVA controllers have batteries that can keep all the data that was not written to the disks for 72 hours.

and also as I understand the leveling is a low-level process to organize the physical disks in such a way that both data is evenly distributed and maximum protection against hardware failures is achieved .
If hard drive is removed or added to a disk group (either manually by you or because of a hardware failure) this process starts.

Check in the storage that, there is any event of such failure.