I've got a customer with an AFF800 with 40 x 7.68TB SSD internal disks. They're using ADP and have split the disks 50/50 across the two controllers into two aggregates giving 113TiB usable per aggregate. They want to add either 12 x 7.68TB SSD or 24 x 7.68TB SSD drives in a NS224 shelf and ADP those disks and add them to the existing aggregates to get the best capacity. Fusion doesn't allow me to do this. So how can I get an accurate usable capacity size for both aggregates?
Hi, you need to manually edit the aggregates in fusion and allowing mixing auf raid types. Background: Ontap will only partition the added drives if they are put in an existing raidgroup. therefore you may need to adjust the raid size settings (if it is ok for the customer). as soon as you create a new raid group within the aggr, it will use whole ssds. you can check it in the technical FAQ for adp.
So for example adjusting the raid groups to 26 will fit all newly added ssds into the existing raidgroups.
However it may not be the best solution, depending on your existing raidgroup size. If you have 20 and resize it to 26, you will have 6 empty partitions within and alle new writes (including calculation auf write stripe) will work with the 6 newly added..so you will have mixed stripes until they have the same usagelevel as the "old" ones. I guess it will not be a big issue with SSDs, but its not best practise.
But just for your main request, you can da it with fusion. see screenshots.
edit: forgot to mention: you need to do a bit of a trick: fusion will not use the disk with 2 partitions, so if you want to add 12 disk (each have 2 partitions) you need to add 24 and than can add 12 to each. because it only is right-sizing them.