Usable disk space AFF400

[fvs0375]

Hello, 

I have a question about the usable disk space, we have a AFF400 4-node metrocluster placed in two locations, 2 nodes in HA configuration per location.

We have 96 NVMe SSD disks, 7,6 TB per disk. In ONTAP, version 9.12P2,  we see that the disk size is 6,99 TB per disk, under Cluster-Disks, but we when we look under Capacity-Aggregate-Disk Information we see that the Usable size is 3,48 TB.

On our FAS8080 cluster, ONTAP version 9.7, we see that the usable size is the same as the disk size, the FAS8080 is a two-node metrocluster, one node per location.

Do we see this difference in size because the AFF400 has a local HA configuration? Or is there something wrong with the configuration in general?

Thank you!

[TMACMD · Accepted solution]

Fabric mcc cannot use the advanced drive partitioning (ADP).  ONTAP will use the whole disk. 

I’d you are using IP based MCC (MCC-IP), then ONTAP will use ADP for much improved space allocation. ONTAP will partition the drives. One small root and two equal sized data partitions per drive. Some root partitions belong to each node for the root aggregate. The data partitions belong to each node. 

this is why your disk sizes appear cut in half. But you will notice twice as many. And behind the scenes, the disks will show like : 1.10.1P1 (or P2 or P3)

[andris]

MetroCluster IP Documentation concerning partitioned disks and the layout on AFF A400:

https://docs.netapp.com/us-en/ontap-metrocluster/install-ip/concept_considerations_drive_assignment.html#adp-and-disk-assignment-on-aff-c400-and-aff-a...