Data Pool went offline, how to remount?

[dealy663]

Hi

I just noticed that my drive enclosure with a RaidZ2 pool of 4 disks was turned off on my system. Not sure what happened, power outtage, but in reviewing the notices in TrueNas Scale I see that has been offline for almost 2 days now. I powered all 4 drives up and the GUI still said that the pool was offline. I couldn't figure out how to bring it back in the GUI, so I did a zpool import from the cmd line.

Now the pool is up but the Dataset still isn't mounted. Hopefully I didn't make things worse with zpool import. Is there a proper way to bring a pool back online and mount it via the GUI? Is the right way only via zfs command line operations?

Gosh I hope I don't have to do a restore of my offsite backup, that will take days and days.

 

[dealy663]

Well I couldn't wait because I was worried about the data. So I restarted... I know probably not the best.

I still need to figure out the best way to resolve this if it ever happens again.

Maybe I'm playing with fire here. These drives are mounted in an external drive enclosure hooked up via USB 3.2. Is perhaps there some potential unsuitability to using an external enclosure like this for hosting 4 drives in a single pool?

 

[LarsR]

The Problem with those usb enclosures is mostly how they present the drives to the os.
Most will show the 4 individual drives, but only 1 generic serial number for all drives and truenas tends to get confused by that and throws erros, or in your case offlines the pool. Most seasoned forum members will tell you to throw those enclosures out the window.

 

[dealy663]

Well I'd hate to have to toss this, because my computer has all available 3.5 drive bays (6) occupied. I just checked in the truenas UI and it shows different serial numbers in the Storage | Disks. Also zpool status shows different UUIDs for each drive in the enclosure.

But if this is to be a common occurrence with offlineing the enclosure, are there any other reasonable external options that would work well. I really didn't expect to exceed my storage options in this homelab/nas build so quickly. The motherboard doesn't have any externally facing e-sata ports not that I'm aware of any e-sata enclosures anyways.

 

[HarryMuscle]

Which USB enclosure are you using?

Thanks,
Harry

 

[dealy663]

This Sabrent USB enclosure

 

[Patrick M. Hausen]

If - which you should not - you import the pool from the CLI, you must use the "altroot" option to get the proper mount point:

Code:

zpool import -o altroot=/mnt <poolname>

To import from the UI, what did you try? It's in Storage > Pools, then click on ADD in the upper right corner, then select "Import an existing pool".

HTH,
Patrick

 

[sretalla]

To be super-clear, what you're doing is asking for trouble.

It may work for some (relatively short) amount of time, but will eventually fail.

USB controllers can't handle ZFS data pool transaction grouping and the high volume of IO that generates in a sustained way.

This post talks a bit about the kinds of problems you get with those (although isn't specific to your USB external enclosure): https://www.truenas.com/community/r...t-multipliers-and-cheap-sata-controllers.177/

Having gone down this road many years ago myself, I can attest that (with 3 dead enclosures) they simply don't last. (I didn't lose any data to it, but I wouldn't take that as a guarantee that it can't happen)

If you want to use a device like that, you'll need to choose another Filesystem (and probably run on Windows to have proper driver support for the port multiplier).