TrueNAS Storage Pool Question

[ssolomon]

I am thinking of moving from a Synology DS1520+ NAS to TrueNAS Core running on a PC build. The Synology has 7x12TB drives in a RAID 6 configuration for a usable capacity of 52.4TB, of which I am using about 20.5TB. I was hoping to keep the cost of the planned build down.

My question is: Can I start off creating a Storage Pool in a "stripe" layout with (2) 12TB drives and then once I migrate the data from the Synology to the TrueNAS, wipe the existing drives... add them to the TrueNAS pool and convert from a "stripe" layout to a "RAIDZ2" layout without losing the data, or do I need to start off with (3) drives using a "RAIDZ1" layout and then expand/convert to "RAID Z2". Thanks in advance.

 

[Heracles]

Hi,

You can not expand the RaidZ2 by adding more drives to it. RaidZ expansion has been discussed a lot and should be coming but is not there yet. Also, you can not convert RaidZ1 to RaidZ2.

Here is something that would be possible but risky because you would drop to 0 redundancy for a moment.
--Remove 2 drives from Synology (down to no redundancy from here)
--Create a stripe with these 2 drives in TrueNAS (no redundancy either) and have these in a first pool
--Move you data from Synology to TrueNAS (still no redundancy)
--Remove the 4 drives from Synology and create 2 pairs of mirrors (these have redundancy but not data on them yet) in a second pool
--Move the data from Pool 1 (stripe) to Pool 2 (mirrors)
--Once done, you are back with redundancy
--Destroy Pool 1
--Create a third mirror with these drives and add it to Pool 2.

You will then have a pool with 3 mirrors, so good performance, good protection and flexible. You will also have 3x 12 TB of usable space, so enough for your data.

Despite this procedure, your situation suggest that you do not have any backups. Know that no single server, TrueNAS or other, can be more than a single point of failure. You need backups for everything you are not ready to loose forever. See my signature for a complete backup strategy.

What you could do would be to get new drives for your new TrueNAS Core and use your actual capacity for a first backup.

 

[Evertb1]

For a long answer study the introduction to ZFS (see my signature). For a short answer: Once a pool is established you need to destroy it before you can use the drives for a pool with another configuration. And that includes loosing the data stored on the pool. Converting is not an available option at the moment.

 

[ssolomon]

Hi,

You can not expand the RaidZ2 by adding more drives to it. RaidZ expansion has been discussed a lot and should be coming but is not there yet. Also, you can not convert RaidZ1 to RaidZ2.

Here is something that would be possible but risky because you would drop to 0 redundancy for a moment.
--Remove 2 drives from Synology (down to no redundancy from here)
--Create a stripe with these 2 drives in TrueNAS (no redundancy either) and have these in a first pool
--Move you data from Synology to TrueNAS (still no redundancy)
--Remove the 4 drives from Synology and create 2 pairs of mirrors (these have redundancy but not data on them yet) in a second pool
--Move the data from Pool 1 (stripe) to Pool 2 (mirrors)
--Once done, you are back with redundancy
--Destroy Pool 1
--Create a third mirror with these drives and add it to Pool 2.

You will then have a pool with 3 mirrors, so good performance, good protection and flexible. You will also have 3x 12 TB of usable space, so enough for your data.

Despite this procedure, your situation suggest that you do not have any backups. Know that no single server, TrueNAS or other, can be more than a single point of failure. You need backups for everything you are not ready to loose forever. See my signature for a complete backup strategy.

What you could do would be to get new drives for your new TrueNAS Core and use your actual capacity for a first backup.

I see. Thanks. FWIW... this is used 100% as a Plex server with a backup of the config/library database on a different system and the actual media files synced nightly to my business Google Drive. More of a DR setup than a backup but cannot duplicate the 20+TB of storage to create a real backup. Since the data is essentially read-only after the first copy and not subject to changes/updates, I am not worried about versioning or similar issues you'd factor into a different use case. Sounds like I ought to wait until the RaidZ expansion is introduced before making the move.

 

[Arwen]

There is a tricky way of doing it. But, this is more for experts in ZFS. So if you need to ask questions, then it is not for you. (I mention it for others that may read this thread in the future.)

All warnings apply, "Here be Dragons, Bears & Lions, ready to eat your data". Make a mistake and you could loose all your data, (if you don't have backups... preferably multiple backups).

1. Remove 2 disks from your existing 7 disk RAID-6, (dropping redundancy to none)
2. Install the 2 new disks as a ZFS stripe in your TrueNAS, (again, no redundancy)
3. Copy the data over from the Synology to the TrueNAS, (this actually makes copy, so some redundancy)
4. Whence the copy is complete, remove the 5 remaining disks in the Synology and make a 7 disk RAID-Z2, (with 2 sparse disks). (This drops any copy backup, and does not add any redundancy...)
5. Copy the data from the ZFS striped pool to the degraded RAID-Z2. (This will make a copy again...)
6. Whence the copy is complete, destroy the ZFS striped pool. (This drops the copy backup...)
7. Use the 2 newly freed up disks and replace the 2 degraded disks in the RAID-Z2 pool

This will work in concept, and give you similar configuration as before, 2 disks of redundancy.