ONTAP Discussions

Max aggregate size calculation


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



Re: Max aggregate size calculation


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


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 😉


Re: Max aggregate size calculation



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


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.

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