Add new disk to pool without data loss

syngress

Cadet
Joined
May 8, 2021
Messages
1
Hi TrueNAS community.
Yesterday I installed TrueNAS for the first time on my home storage server.
I have 4 different size disks, and each one of these disks has been added to a separate Data VDevs.
I use striped option.
Additionally, an M.2 256GB NVMe drive has been added as a cache drive.

Now in count I have one big 12TB data storage with compression turned off for better performance.
I do not store data on these disks that are very sensitive to me and cannot be lost.
However, I have some movies there that I would not like to lose by a stupid mistake, so I allowed myself to write here ;)

What I try to do is to add next new 10TB HDD to existing (12TB pool), can I add it without losing data?
 
Joined
Sep 13, 2014
Messages
149
Are you aware that the loss of any vdev within a pool means the total loss of the entire pool? If any single disks fails, you lose everything.

Adding another, single disk to a pool consisting entirely of striped vdevs is easy... but you won't find many people that will tell you it's a good idea given that it adds another potential point of failure / total data loss.

[EDIT] One other thing to note about using single disk, striped vdevs... or more to the point, not using mirroring or RAIDz*, is that many of the features that attract users to ZFS, such as it's self healing abilities against bit rot, bit flips, and your various other nasties, only work if you are using mirrored vdevs, or RAIDz*. With a single disk vdev, ZFS can still detect data corruption but basically, when corruption is detected, ZFS has no way of repairing it.
 
Last edited:

danb35

Hall of Famer
Joined
Aug 16, 2011
Messages
15,466
with compression turned off for better performance
CPU is much faster than spinning rust. With compressible data, you'll probably find that enabling compression increases performance (and with incompressible data, there won't be any difference).

As noted above, it's trivial to add stripe in another disk with your pool. But I'm not sure why you're tying that to "movies there that I would not like to lose by a stupid mistake"--striping in another disk would increase your risk of total data loss.
 
Joined
Sep 13, 2014
Messages
149
I just wanted to expand on my previous comment.

@syngress, if you don't fully understand my previous comment, then all you have to do is ask and I'll explain it in more detail. You could / should also look at the first and second links in the "Useful links for new users" section in my sig, so that you understand the ramifications of adding disks to your TrueNAS server.

If you understand the risks you are taking with adding another disk to your pool, then I don't mind helping you with the process but I want to make it clear that I wouldn't advise adding striped vdevs for 99.9% of users and use case scenarios, including your own.

Finally, if you're worried about losing your pool. Then there are plenty of users here, myself included, who will help point you in the right direction and advise you on your best course of action to add some redundancy / protection against data loss to your server.
 
Top