We have a 2650 with 48 disks, 4 SSD (400G) as flash pool and 44 SAS (900G) disks split in 2 aggregates 21 to each aggregate with max raidsize of 21.
The aggregates need to be expanded and the site is small so a a shelf of 24 1.8T disks was purchased. the question is what is the best method for additional capacity? Aggregates are required to be in pairs as we have Redundant systems on separate aggregates.
These are the options that I have come up with :
Add a new 11 Disk RG to each of the existing aggregates
Create a 2 new 11Disk Aggregates and give 1 flash pool allocation unit to each
Increase the maxraidsize to 28 and add 7 disks to each aggr
This is all in ontap 9.3p6 , I also have a question about reallocation scans and whether they are still required, needed. Volume or Aggregate....
Go with create two new aggrs option if you need to split the workloads like that. Otherwise I would do a single one, more spindles and capacity. It's not a best practice to mix disks like that.
if you're creating new aggrs, no need for reallocation. If you were to be adding to existing aggrs, you can run reallocation but IMHO only needed if you're adding disks to the aggr to increase performance, if you're just adding for capacity WALF will eventually start writing data in to the new disks.