How to recover data from dead hard drive.

[Frank Leonhardt (m)]

On 14 October 2017 21:21:15 BST, tech-lists <tech-lists at zyxst.net> wrote:
>Interesting thread.
>
>I have a similar problem, this time with a failing (now failed) disk
>that had freebsd-11-stable installed with the root-on-ZFS option. I
>manged to dd over ssh an image of the disk. However, I've not been able
>yet to mount the image to get the data. I think it's ZFS in the image 
>that's causing the issue. I've tried to spin up the image in bhyve on
>another system. It gets past the demon graphic, tries to boot but drops
>
>to the mountroot or mfsroot (can't remember exactly) prompt. No matter
>what I enter there, it still won't boot. What it defaults to is what
>it used successfully when it was on the (now failed) hardware.
>
>Can anyone tell me how to mount and recover the image? 

If you're lucky this is caused by bhyve. However, by this stage, if you're booting from a once-working boot drive then the ZFS stuff should have been brought in by the loader, allowing it to mount the FS  and load the OS.

Have you tried specifying a different device? (Its safe to guess).

I'd probably mount the image using mdconfig on a ZFS enabled machine (type zpool to check it's been compiled with the right modules) and see if it can auto-mount. Easier than sorting out boot problems, especially if the boot partition has been clobbered.

ZFS is surprisingly good at reassembling stuff from odd locations using GUID  metadata. Only worry I have is that its part of a striped vdev, which will allow you to boot that far using code duplicated on each drive, but then no further.


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