Backing up to an External HDD

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ARNiTECT

Member
Jan 14, 2020
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What is the suggested method for reliably replicating filesystems to a removable external USB HDD?

I just tried to replicate a number of ZFS filing systems to a USB connected 5TB 2.5" HDD and midway through the replication, the drive reported errors and now I can't remove the new pool it is/was on.

Using ESXi 6.7, I pass-through 'Host USB Device', select my drive.
In OmniOS 151034/Napp-it 20.01a5 Pro I see the new drive and create a new pool Tank4 with the usb drive as a basic vdev.
I set a job to Replicate from Source Pool/ZFS: Tank2/Archive to Target Pool: Tank4 and as expected it created a new filesystem under pool Tank4.
The first 20GB filesystem test went ok, then I tried a different 500GB filesystem and when I returned pool Tank4 was no longer listed under ZFS Filesystems and in Pools it's state is unavailable, status: 'One or more devices are faulted in response to IO failures'
'cannot open 'Tank': pool I/O is currently suspended'
I am running the drive through WD Data LifeGuard (9 hours to go), but it is a fairly new drive with very little use.

Are there issues with using USB connected drives for replication, or assuming the drive/cable/controller are ok, it should work?

How do I remove pool:Tank4 state: UNAVAIL?
 
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gea

Well-Known Member
Dec 31, 2010
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You can only export/ destroy a ZFS pool in online or degraded mode. When a disk fails with a basic pool on it, the pool is unavail with pending io and ZFS is waiting to finish the waiting io. You need a reboot to solve this situation and remove the failed pool.

There has been a problem with Illumos and large USB disks but this should be solved in current OmniOS, Bug #11952: large USB hard disks experience I/O failures - illumos gate - illumos so this seems more a general problem with USB reliabiliy together with some disks or chipsets. You may try USB2/3 or a different controller/ setup as your problem seems USB and not the disk. In general an eSata or a disk that you can insert into the hotplug capable backplane is not only faster but more reliable.
 

ARNiTECT

Member
Jan 14, 2020
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7
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Thanks Gea, I'll wait until this evening and restart the server and try again.

I used USB2, so will try adding a USB3 controller in ESXi to use host USB devices.

Another issue might be that I currently have a complicated USB setup in ESXi. OmniOS & my Primary DC installed on an ESXi datastore on an SSD connected using an SATA-USB adapter; so the USB Arbitrator service is disabled and I have then specifically re-enabled the pass-through of the 5TB USB-HDD. So far I haven't had any issues with this setup. I do have an NVMe Optane 900P, which I plan to use instead ...and reset the ESXi USB settings back to their defaults.

I have a number of 4-5TB ext 2.5" USB-HDD which I cycle for backups (pass-through to windows server VM), but would rather use ZFS replication.

I will look into external hot-swap esata drivebay/docking station.
 
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ARNiTECT

Member
Jan 14, 2020
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I decided to abandon USB for backup and instead shuck a couple of 5TB Seagate 2.5" portable drives and replace my 6x2.5" drive bay with a 4x2.5" drive bay that accepts 15mm thick drives.
In the future, I will experiment with passing through USB to OmniOS, as I think it would still be useful.