Hello,

I'm switching to ZFS and have been testing a setup on a mini PC with a USB enclosure. I created a two-drive ZFS mirror for my SMB shares. During testing, I removed one drive from the enclosure and found I could no longer access the ZFS pool or shares. I expected the mirrored pool to remain accessible in a degraded state until I replaced the drive.

My concern is that if I'm away from the server and a drive fails, the entire system might lock up. While I know a USB enclosure isn't a supported configuration, my plan is to use two NVMe drives internally within the PC. I want to confirm that a mirrored ZFS pool will indeed remain operational if one of these internal drives fails.

On a side note, if I replace the removed drive and reboot, the pool does rebuild itself successfully.

Thanks

A mirror should work with a single device, please post the diagnostics.

Here's a screenshot and the diagnostics as it's failing. Thanks!

testtower-diagnostics-20250621-1509.zip

Edited June 21, 20251 yr by dxb

There are write errors on both devices, mirror can't help with that:

Jun 21 15:01:51 TestTower kernel: usb 4-4: USB disconnect, device number 2

Jun 21 15:01:51 TestTower kernel: sd 0:0:0:0: [sda] Synchronizing SCSI cache

Jun 21 15:01:51 TestTower kernel: sd 0:0:0:0: [sda] Synchronize Cache(10) failed: Result: hostbyte=0x07 driverbyte=DRIVER_OK

Jun 21 15:01:51 TestTower kernel: sd 0:0:0:1: [sdb] Synchronizing SCSI cache

Jun 21 15:01:51 TestTower kernel: sd 0:0:0:1: [sdb] Synchronize Cache(10) failed: Result: hostbyte=0x07 driverbyte=DRIVER_OK

Both devices dropped offline at the same time, note that USB is not recommend for array or pools devices.

Thanks. I had a two-drive RAID enclosure with one USB-C cable connected to the server. I got a second USB-C enclosure, and now I have two enclosures connected to separate ports. The ZFS pool is working as expected. Thanks again!