Expanding RaidZ1

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Aug 2, 2017

I apologies if this topic has already been covered in another thread, but from what I found was not an exact answer for what I needed.

Basically, to keep this a very short thread, here is my setup.

2X X5650 6C/12T CPU's
48 GB ECC ram
8gb Kingston USB (FreeNAS installed on)
4X Seagate 3TB HDD's in RaidZ1 (MainShare)

Total usable space is a little over 7TB with parity.

Mostly the data on here is basic media, Movies, TV Shows and some other personal data, nothing mission critical.

I do have a backup server (mentioned in another thread I finally got it to work) however this runs Window Server 2012 r2. Similar setup storage wise and does night file backups of the main server.

Anyways, my questions is this: At this current moment, I am about 75% full and I estimate that within the next 2-3 months I will reach the limit of the storage. How difficult is it to expand my current volume (MainShare) with an identical Seagate 3TB HDD?

Per my understanding, I just have to go to Volume Manager, Change the "Volume to extend" to my "MainShare" and once I get the new disk installed, select it and then click "Extend Volume" on the bottom?

Don't mind the available disks shown in the above screen shot, these are not going to be installed in the system.

Does FreeNAS take care of the rest and then my theoretical max storage should be around 9TB correct?


Documentation Browser
Jan 12, 2015


Hall of Famer
Aug 16, 2011
How difficult is it to expand my current volume (MainShare) with an identical Seagate 3TB HDD?
It is not possible to do that and retain redundancy. If you do what you're proposing, the new disk will be striped with your RAIDZ1 vdev. When (not if) the new disk fails, your pool will be lost. There's a project in progress to allow you to do what you're trying to do, but I expect it to be two years at least before it makes its way into FreeNAS.
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