2011-07-11 11:18 AM
When adding a new shelf of disks into an existing aggregate, will there be any performance issues initially? Eg will ONTAP/WAFL try to balance the existing datya over the new disks so all is balanced?
I think the concern is whether ONTAP will look for the most free space and hammer the new disks.
Can you please comment on this?
2011-07-11 12:05 PM
Per my best understanding
When you add new drives, create Aggr/RAID groups as per storage best practices.
RAID groups are sized such that the total number of disks are balanced among multiple RAID groups under same Aggr.
Having more number of disks in Aggr will help in not hitting diskbound boundbottlenecks
When new disks are added to the Aggr, ONTAP does not re arrange the blocks immediately,but eventually as updates are happening on the files it will get distributed.
Also refer to man page of "reallocate" command
2011-07-11 03:43 PM
if possible create a new RAID group
After new disks are added to the aggregate WAFL directs most writes to the new disks
creating a complete RAID group is a good practice