In my experience using a USB drive for backup is perfectly reasonable.
All the caveats are technically correct but really only apply to users who try to use a couple of USB drives for their main storage pool. Discouraged for valid reasons.
It’s not that “ZFS does not play well with USB”. TrueNAS does not play well with USB for at least these reasons:
- TN relies on the drive serial number for drive identification and might become confused to a point that it’s losing an entire pool if all drives have the same serial. As USB frequently does.
- USB drives are more difficult to monitor with smartmontools although many USB-SATA controllers are supported today.
- The original USB was really not designed for mass storage but for keyboards, mice and printers, and it still shows - drives might just “hang” occasionally.
So that’s (as I see it) why you should not have your 24x7 available pool on USB drives.
But for backup - which is the topic of this thread …
What’s wrong with connecting a number of large single disk storage thingies that today are insanely large and also dirt cheap because they are considered consumer products?
And when you do that of course you want to use ZFS on them. Because checksums. Because snapshots and replication. Etc.
No, ZFS does not “not play well with USB”. I have USB connected enclosures with M.2 NVMe drives in them that I use with my Mac daily. With ZFS.
So my recommendation would be:
- Given the limits of USB storage which do exist do not try to create a pool from multiple drives.
- Get drives as large as you can afford, create a pool from a single drive, replicate what fits to that single drive pool.
- Switch drives in rotating fashion instead of pool/vdev based redundancy.
You can have all your pools in a rotating set of drives named the same, so a replication task will fit.
- Connect drive.
- Import pool.
- Manually trigger replication task.
- When done, export pool.
Repeat with second, third, … drive.
Kind regards,
Patrick