Wipe ZFS signatures from a disk

I recently made a silly mistake. I was looking a TRUEOS DVD and I thought it was a live system, but it was an install DVD. It wrote a ZFS filesystem all over my 500Gb SSD… wiped everything, even grub on the MBR.

Fortunately I had clonezilla backups. They were saveparts images - ie images of partitions.
So I had to put the partitions back before I could restore filesystems. I did that with gparted…made a GPT partition table and created 7 partitions … EFISystem, bios-boot, 4 x ext4 partitions, and a swap partiton.

Went ahead with clonezilla and restored my Debian filesystem and my data filesystem.

Then I had to install grub. Used SystemRescueCD for that.
Also had to remove grub.cfg from the Debian filesystem, because I had reinstalled Debian to a different partition.
Also had to edit /etc/fstab to fix the UUID’s

Then I could reboot and get the grub> prompt. From there I booted Debian with

grub> linux /vmlinuz root=/dev/sda4
grub> initrd /initrd.img
grub> boot

And Debian booted . So then from within Debian I could configure grub with update-grub.
Then a reboot showed that i had a grub menu and could boot from that.

OK success … so I thought. But

  1. it took forever to boot
  2. when I looked at the disk from within Debian, with the Gnome-disk-utility, it looked normal, but when I looked with gparted it said the entire disk was one ZFS partition!

What is going on? There must be some residue of ZFS on the disk?.. much research, and I finally find a tool called wipefs which I can use to check the disk.

Now, wipefs sounds like a dangerous tool, and it is, so another clonezilla backup first.

Then do this

root@mary:/home/nevj# wipefs /dev/sda
sda    0x7dc00      zfs_member      
sda    0x7d400      zfs_member      
sda    0x7d000      zfs_member      
sda    0x7cc00      zfs_member      
sda    0x7c800      zfs_member      
sda    0x7c400      zfs_member      
sda    0x7c000      zfs_member      
sda    0x7bc00      zfs_member      
sda    0x67800      zfs_member      
sda    0x67400      zfs_member      
sda    0x67000      zfs_member      
sda    0x66c00      zfs_member      
sda    0x200        gpt             
sda    0x6fc86d5e00 gpt             
sda    0x1fe        PMBR            

It lists many items that are called signatures… most of them zfs_member, but at the end my GPT partition table, another copy of the GPT partition table at the top of the disk, and the PMBR (protective MBR).

We can use wipefs to remove these zfs signatures as follows

root@mary:/home/nevj# wipefs -o 0x7dc00 /dev/sda
wipefs: error: /dev/sda: probing initialization failed: Device or resource busy

but, hang on, the disk is mounted and it can not do it from within Debian

So back to SystemRescueCD, and do from there

wipefs -o 0x7dc00 /dev/sda
wipefs -o 0x66c00 /dev/sda

Yes I had to type the whole 90 lines of wipefs... without mistake.

Reboot Debian, and it is right. Boot is now normal speed, and gparted finds my 7 partitions now. Do another backup .

I just thought this story might be interesting. Anyone can make a mistake. Recovering is not always easy … and is impossible if you do not have a backup…
I quote @Akito “Always do a backup”



One more thing I need to do, set a timeshift bkup!!!

@4dandl4 ,
Yes any backup is way better than none.
Do it before you change the DE.