Aggregate Expansion

[cshenberger]

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....

[SpindleNinja]

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.   

[cshenberger]

Why 2 new isntead of just expand?   still means that reads will come from 11 spindles instead of 32 ? 

if you reallocate for performance does it have to be at volume or aggregate? 

[SpindleNinja]

Give section 4.7 a read over in this TR https://www.netapp.com/us/media/tr-3838.pdf   It's doable to add mixes sizes,  but not recomended.     One of those,  just because you can,  doesn't mean you should kinda things.      

Mixing speeds, unless SSD+ spining disk for flashpool, is also not recomended.  

You will probably want to start with volume.   This FAQ might be helpful for you reguarding the reallocation.

https://kb.netapp.com/app/answers/answer_view/a_id/1001019/~/faq%3A-reallocation-for-provisioned-storage-