Hi Guys.
I currently use TrueNAS Scale - Electric Eel.
I am considering expanding my storage pool now it is an option.
Due to limited space in my case though, I want to know, is it possible to migrate 4 of my 8 drives to a DAS in JBOD mode?
The 4 in question are their own Pool, and the remaining 4 are also in their own Pool.
Since the expansion feature is so new, I haven’t seen anyone answer this question yet.
Thanks in advance
In theory - yes. ZFS Pool disks are not fussy about where they are plugged in and don’t mind being moved around.
However
It depends on wjhat the DAS is - and how its connected as to how well this will actually work.
This is almost certainly bad, unless you’re thinking of something like that:
The correct solution would be an external SAS shelf with a -4i4e HBA, or an expander.
Well it is a Qnap TR-004. USB3 connection. It can work in RAID, or JBOD modes. It does expose SMART info to the system - or at least it does with Windows.
It isn’t planned for a permanent solution. Just while I add drives to my Z1 pool that will be remaining the main Case. I can then migrate the contents across to the main Pool.
USB can be problematic:
Some hardware RAID enclosure’s JBOD mode are not true direct access to disks. See above resource for potential problems.
That is nice, and if it worked with TrueNAS, great. But, that is not the only problem, see above resource for further potential problems.
To sum up, USB attached data disks for ZFS are noticeably less reliable than SATA, SAS or NVMe. You may have no problems in 5 years, but the only way to tell, is to try it. And then, if you have problems, the “correct answer” is going to be use a proper disk interface method.
…and if you have problems with a raidz1 in a USB enclosure it may well be too late to fix it.
Well I have a work around I can try.
My motherboard has all it’s SATA connectors because I am using an Add in card,.
So I can plug the new drive into it and put it in a Caddy in my unused 5.25" bay. I can then add the new drive to the Pool. When I get another drive, I can do the same, but just keep it external until I migrate everything across. I will then be able to remove the old Pool and just run with the one.
Would I have to rebalance the Pool before I do the move?