Space calulations when creating new Aggregate on AFF A250

[MK429]

I have a new AFF A250 running ONTAP 9.13.1P10 it has 24 x 7.68TB NVME SSDs 

When I go to create the new aggregates, the system proposes :

Two aggregates each of  23 x 3.48TB  = 65.8TB   ( 2 disks lost to raid so 21 x 3.48 = 73.08 ) 

65.80TB is 10% less than 73.08TB  - Typically this would be the 10% WAFL overhead, however as I am running out of the box ONTAP 9.13.1 I would expect the WAFL overhead to be 5% and the usable aggregate to be 69.42TB

My question is : when a new aggregate is created does it a by default have a 5% Aggregate Snap Reserve factored in, therefore I am seeing 5% WAFL overhead + 5 SnapReserve or do I have an issue with the AFF where it is not setting the WAFL reserve to 5%

It may seem a small amount of space for that aggregate example but over the whole cluster its around 40-50 TB we are missing.  ( other nodes on the cluster are C400 which much larger disks ) 

Thank you.

[TMACMD]

Building out an A250 with 24 x 7.68, you whould end up with:

root/vol0 = maxraid-10, 8 root partitions, 2 root-partitions for Parity  = 23.4G x x = 168.3G (default min-root)

data/aggr = maxraid-22, 20 data paritions, 2 data partitions for parity = 3.48T x 20 = 66.15T (2 spare data partitions)

-- OR --

data/aggr = maxraid-23, 21 data paritions, 2 data partitions for parity = 3.48T x 21 = 69.46T (1 spare data partition)

If you are deviating from these numbers, maybe the system was not initialized with all 24 disks in the system. I see that all to often. Using the built-in process to auto-create the aggregates, it will usually keep one partition by default as a spare.

[MK429]

Hi

Traced the problem to the way the system manager UI calculates aggregate capacity,  the UI factors in both the 5% WAFL overhead and 5% agg snap reserve when estimating the size of the agg.

However when you actually create the aggregate it doesn't apply the 5% snap reserve setting , thus giving you an extra 5% of space ( which matches what NetApp Fusion quoted )  very frustrating especially when you have large arrays of 15TB disk and suddenly 5% is a lot of space!