Expanding a freenas data pool

[accessgp]

Hi, I have an existing pool of 8 x 4TB configured in Raid Z2, now I have 5 more drives 4TB x 5. Can I add these new drives in a raid Z2 configuration to expand my existing pool or not? I am open to ideas or suggestions as I am a newbie to freenas

 

[garm]

Sure, you can have as many vdevs as you want. It’s unwise to have unbalanced vdevs, but it will work and it won’t break data. It will affect performance, but you probably won’t notice it. Just make sure to burn in the drives. If you add the new drives as a new vdev to your pool and you lose three of them you loose the entire pool, that includes your old vdev as well.

 

[pschatz100]

Sure, you can have as many vdevs as you want. It’s unwise to have unbalanced vdevs, but it will work and it won’t break data.

Why is it unwise to have "unbalanced vdevs"?