Data ONTAP Discussions

Adding disks to existing aggr

I am currenly running and have an aggr with 16 disks and RAID size of 16. I want to increase the aggr with the 300GB FC drives available. What would be my best practice solution for this to get the best performance? Can I just add the disks to the same RAID set?

Also, when trying to expand the aggr from FileView, the disks are not listed. I have 18 spare disks available and they do show when creating a new aggr. Has anbody seen this issue?


Scott Lau

System Admin

HUB International Inc.


Re: Adding disks to existing aggr

I would be careful adding them to the same RAID set, although it's possible if you increase the RAID group side.

If you keep the RG size at 16 and you add disks, you will start a new RG with new parity disks (assuming RAID-DP here).  The best practice here would be add in sets of 8 or 16 for performance purposes.

As far as the FilerView issue, I'm guess I'm curious what size and type of drive are currently in your aggregate as that might affect its behavior.

Re: Adding disks to existing aggr

The disk sizes are the same (300GB FC) listed as 268GB

Re: Adding disks to existing aggr

Ok..that's a good thing.  Assuming you have enough it should let you add them.

I'm not a FilerView expert, so you can always work with support on that part, but the CLI is pretty simple:

netapp> aggr add <aggr_name> X@300

Where X is the # of disks you want to add.  Again if you don't increase the RG, this will make your first 2 disks parity disks.

Re: Adding disks to existing aggr

If the RG is not increased, will it create the second RG automatically (i assume...but we all know that that means right) and at what size?

Re: Adding disks to existing aggr

The new RG will be created automatically.

If the RG size is set to 16 & you actually add less than 16 new drives (say 11), it will create a new RG containing all new drives.


Re: Adding disks to existing aggr

Yep.  ONTAP is smart enough to know that when you hit the RG size, it will start a new one automatically (by making the next 2 disks parity, then data drives up until the new RG hits the RG size, then it will start again.

Just be aware that adding disks to an aggregate is not easily reversible, even right after you do it.  The only way to pull a data disk out of an aggregate is to destroy the aggregate and rebuild it.  It's one of the few things in ONTAP that is difficult to undo.

Re: Adding disks to existing aggr

As far as adding disks through FilerView is concerned,selecting "Manual" for disk selection should list all the disks.

Re: Adding disks to existing aggr

NOPE! The list is empty even if I check the Diff RPM option!!! Some funky bug maybe in version upgrade that was done few months back! I will check with Netapp and post back later!

Re: Adding disks to existing aggr

In Aggregrate Manage page, click on the aggregrate. There is a option to Add Disks to Aggregrate. And inside the wizard there is a option for manual selection. Selecting the manual option will list all the available Disks and user can select as many disk they want.