topic Re: Max aggregate size calculation in ONTAP Discussions

Max aggregate size calculation

LORENZO_CONTI — Wed, 04 Jun 2025 12:38:20 GMT

Hello,
we were adding some disks to existing aggregate and got this error message:

Cannot add specified disks to the aggregate because the new aggregate size would exceed the system limit. Limit: 400.00 TB.

I found this old article on how to calculate max disk per aggregate: https://library.netapp.com/ecmdocs/ECMP1196986/html/GUID-F47A5CA3-D2F7-4D72-829B-2D1C7F68BC7E.html

It says: "For calculating how many disks you can put into an aggregate before you exceed its maximum size, you use the right-sized, or usable capacity of all data disks in that aggregate."

If I use the usable-size as reported by Ontap 9, our disks have a size of 2.42TB; there are currently 165 data drives on the aggregate, this result in 399.3TB (but the usable space is 359TB, because of WAFL overhead i suppose).

Do you agree with that?

Thank you

Lorenzo

Re: Max aggregate size calculation

cedric_renauld — Thu, 11 Apr 2019 11:48:35 GMT

Hello, Lorenzo

You'rez right ... often you ritch first the max capacity before the max disk number

If your limit is 400 To, you cannot grow up your AGR over this limit

Re: Max aggregate size calculation

LORENZO_CONTI — Thu, 11 Apr 2019 12:12:55 GMT

Hi Cedric,

thank you for the reply.

Better to keep in mind about that when planning storage design. It's quite frustrating to add full loaded shelves and cannot use all the drives on them 😉

Lorenzo

Re: Max aggregate size calculation

cedric_renauld — Thu, 11 Apr 2019 12:21:20 GMT

Sure,

But you can create another AGGR ...

You just need carefull about the disk nimber in your RG before

I'm Sorry for you

Bur just a last pair of questions :

- DataOntap version

- System FAS xxx

Maybee with an Dataontap update you can have more capacity supported

Re: Max aggregate size calculation

LORENZO_CONTI — Fri, 12 Apr 2019 10:16:02 GMT

Hi, it's a FAS8060 with 9.1P15 and no, I've checked on hardware universe, we cannot go beyond 400TB (360TB) ever with 9.5.