[OmniOS-discuss] Request advise on pool upgrade

[Bob Friesenhahn]

On Tue, 6 Feb 2018, Andries Annema wrote:
>
> Right now I am leaning towards options 2 or 3, with maybe a little preference 
> for option 3, I think.
>
> Any thoughts you guys can share on this matter? Would appreciate it. Thanks!

Since your pool is already excessively full, adding a new vdev would 
result in most of the freshly-written data being written there.  This 
would result in reduced performance as compared to uniformly available 
space in the vdevs.  There are things you can do after adding 
another vdev to rebalance the data across the vdevs.

Smaller size disks are better from a recovery/resilver standpoint. 
More disks are better from a performance standpoint.  Replacing a 
drive with 8TB of data would take a very long time.  4TB disks are 
already huge.  Larger size disks are often slower than smaller disks.

Lastly, there is always the "Let sleeping dogs lie" proverb, which 
suggests that not touching existing disks is less likely to result in 
trouble than adding additional disks.

I prefer option 1 to add a 3rd vdev with the 4TB disks.

Bob
-- 
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/