We created a raidgroup size for an aggr of 5 disks instead of leaving it the default 16. We now have 2 raid groups, rg0 - 5 disks, rg1 - 4 disks. I know we can expand the raid group size, however is there a way to eliminate rg1 and move, replace, or recover its disks with out blowing the whole aggr away?
No, once the drives are part of an aggregate, they can't be taken out (with the exception of failing them, of course - but that won't accomplish what you want). I have wanted to do similar things many times - it'd be nice if you could balance drives out like you can with Oracle ASM disks...
Out of curiousity, why did you choose a RG size of 5?
It ended up 5 by accident / lack of attention to detail I think - this filer is at our DR site and it’s also an office, our support guy there has been learning the NAS as a backup, we were moving all of his share data to the NAS from a file server and I told him to create an aggr with 5 disks, which he did and has done so before, the issue just came up when we needed more space, I went to add another disk and noticed the raid group issue. I guess he changed the raid group to 5 thinking it was the number of disks, and he apparently added three disks on his last expansion. I went back and checked all the other he has done and they are correct – not paying attention I guess.
Yes a way to reallocate disks / RGs or shrink aggrs would be nice. I have several times needed to shrink / recover disks from an aggr after a project is over but there is just a little bit of data remaining, so I have a catch-all aggr that I mirror the last bits to until they can be deleted so I can blow away the original aggr. Not hard just time consuming - easy to give, hard to take back.