smartctl against boot pool produced I/O error

[rmccullough]

I ran smartctl -x /dev/ada0, which is my boot pool. I was poking around the temperature warning levels for the drives in my server and thought I should check the threshold of my boot SATA DOM.

The command seemed to hang after about a page of output, and then via my IPMI interface I saw this error:

I tried to reboot the system, but it became unresponsive. So I used my IPMI interface to power off the system, and then power on.

Should I be worried about this?

 

[Samuel Tai]

Even if you toasted your SATA DOM, boot pools are easy enough to reconstitute, assuming you've saved your config offline somewhere, so it can be reimported later to transform a vanilla new install to your saved configuration. The more pertinent question is whether you backed up your config or not.

 

[rmccullough]

My config is backed up daily to my main pool. Is this foolish? Do I need to be backing up my config to different storage?

 

[Samuel Tai]

The main pool backup is better than nothing, but ideally you want at least 2 copies outside the server entirely. I keep 2 copies in a BitLocker-encrypted thumb drive I always keep with me, and another 2 copies in my OneDrive FileVault, so I always have at least the last 2 known good configs ready for recovery.

 

[rmccullough]

Ok, fair point. I may put a few copies in my cloud drive.

 

[rmccullough]

I would at some point like to get a thumb drive configured as a backup boot device. How difficult is that? Pretty straightforward?

 

[Samuel Tai]

I would at some point like to get a thumb drive configured as a backup boot device. How difficult is that? Pretty straightforward?

Easy-peasy. Just add the new thumb drive as a mirror in the GUI. When the mirroring is complete, remove the thumb drive. Then when the GUI complains about the unavailable member, remove it from the mirror.

 

[rmccullough]

Could I leave the thumb drive plugged in so that it is kept in sync with the primary boot drive?

 

[Samuel Tai]

Yes, that works too.

 

[rmccullough]

Ok, so I bought a thumb drive to use as my mirror for my boot drive. When I tried to attach it to the boot pool, I received an error that it is too small. My current boot drive is 29.82 GiB whereas my new thumb drive is 28.65 GiB.

Can I resize my boot pool so that I can mirror it with this thumb drive?

 

[Samuel Tai]

Easier would be a reinstall onto the thumb drive, and a reapplication of the config, and then mirroring your SATA DOM to the thumb drive.

 

[rmccullough]

Is this pretty straightforward? I would love to mirror from the existing drive just because it has all the previous updates in case I need to revert a boot environment.

 

[Samuel Tai]

So far as I know, it's not possible to shrink a ZFS partition, which is what you would need to do as you propose. You would have to sacrifice your previous boot environments. Alternatively, you can just get a bigger thumb drive.

 

[rmccullough]

It was cheaper to just buy a 64gb thumb drive than to reinstall, etc. Not worth my time for the $4 difference... Thanks though. Resilvered last night. Need to test booting from the USB at some point now.

Am I right to infer that if that pool is made up of a SataDOM and USB thumb drive in a mirror, that I can boot to either, make changes, then reboot into the other device and it should be in sync and a seamless experience?

 

[Samuel Tai]

Am I right to infer that if that pool is made up of a SataDOM and USB thumb drive in a mirror, that I can boot to either, make changes, then reboot into the other device and it should be in sync and a seamless experience?

Pretty much.