Raidgroup disk addition ONTAP 9.5

[S-Sahu]

Was trying to look for supporting documents for the below query but couldn’t fine any, the major concern is when we are going to add the single disk to make Rg1 to 22 disks will there be any major performance impact?

We have a hybrid aggregate which has two raid groups contains 22 and 21 disks. We have recently added one disk shelf wit 24 disks. What is the best practice to create 3^rd raid group of 22 disks or 21 ? do we need to add one drive in 2^nd raid group in order to bring it to 22 disks count which has 21 disks.

. If current raid groups in aggregates are not have equal drives (last one has 1 drive less) then when we add  more aggregate then do we need to equal the older raid group before creating the new one.

Current Raid group disk count

RG0- 22

RG1-21

Before creating RG2 do we add 1 drive in RG1 or we can go ahead and create new raid group RG2 with 22 drives. What is the best practice ?

[SpindleNinja]

I would add the one and then create the new rg,    for spinning media (or hybrid in your case)  you want to have your rg as balanced as possible.      So 22,21,22  or 22,22,21   shouldn't matter.  I would do 22,22,21 personally.   

If you just let ONTAP do it's thing with the aggr disk add command it should just automatically fill rg1  and then create a new rg with the remaining disks.    use the -simulate flag to see what it'll do. 

[S-Sahu]

Thanks the main concern is will it have a performamce impact I mena when the additional disk is filling up will it create any bottle neck.

Thanks

S

[SpindleNinja]

Nope,  no perf issues.   It will just start using that disk to write blocks too.  

if you did something like 22,21,3  you would have issues.