[zfs-discuss] recovering zfs partition tables/data

cmc iucounu at gmail.com
Sun Dec 4 13:51:57 EST 2016


Hi,

In the process of replacing a failed drive for a raidz2 set, and while the
machine was powered off, a cable was unplugged which connected 3 drives to
the sata HBA, and when the machine booted up, it of course reported the
pool as unavailable. I powered the machine down again, plugged the cable
back in, but the HBA no longer recognised the drives. I added them back as
RAID 0 single volumes, as other RAID controllers I use for ZFS use this
configuration for single drives. However, I forgot that this particular
controller has 'pass-through' mode, and when the machine booted up, it
could not find the partition tables created by ZFS. So I rebooted and set
it back to pass-through in the HBA BIOS, but the tables were gone, I assume
the HBA overwrote it with a RAID signature. I am hoping that the controller
does not overwrite the entire disk (it showed no signs of overwriting large
numbers of sectors when I created the raid0 config), and thus that most of
the data will still be there. My hope is then that I can then perhaps
re-create the ZFS partition table without killing the data.

I'm trying TestDisk as a recovery tool, but it does not support ZFS and
reports HFS partitions and 'MS Data' on the drive. I thought I could dd the
contents of each of the drives to another set of drives (1:1), and then try
to create a partition table somehow manually, though I'm not sure how to do
this.

Anyone with any tips or ideas on how to recover from such a situation? Many
thanks in advance for any help.

Cam
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