topic Adding a new shelf of disks into an existing aggregate in ONTAP Discussions

Adding a new shelf of disks into an existing aggregate

biescas — Thu, 05 Jun 2025 06:50:50 GMT

Hi,

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?

Regards,

Adding a new shelf of disks into an existing aggregate

baijulal — Mon, 11 Jul 2011 19:05:54 GMT

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

Adding a new shelf of disks into an existing aggregate

nitish — Mon, 11 Jul 2011 22:43:46 GMT

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