[OpenIndiana-discuss] Destroying a zombie pool

[Reginald Beardsley]

 It's actually quite safe as long as the target device is correct.  Cutting and pasting with the mouse from the output of "zfs import" recommended.   There are potentially two labels of 256 kb at the start of the slice and two at the end.  I use dd to clear old labels and other stuff off disks  all the time.  I also  used it to clone OS installs back in  SunOS 4.x times.

For a small slice just do the whole thing:

dd if=/dev/zero of=/dev/rdsk/c?d?s? bs=512

NB: I was a bit numb at the time and actually specified bs=4096.  No harm done.  I'd just gotten a bit 4kb sector fixated.


for big slices two operations are quicker:

dd if=/dev/zero of=/dev/rdsk/c?d?s? bs=512 count=2048

dd if=/dev/zero of=/dev/rdsk/c?d?s? bs=512 skip=NNNN

where NNNN = number of sectors in  slice minus 2048.   Do the whole slice if you're not going to overwrite it and are concerned about data leakage.

On 4kb sector disks, the bs, skip and count values will need to be adjusted appropriately.

dd is actually very well behaved, but  user's  have been known to be inattentive ;-)

Here's where I found the ZFS info:

https://maczfs.googlecode.com/files/ZFSOnDiskFormat.pdf‎

FWIW I rebuilt my Solaris 10 system from a 2 disk  900 GB  root pool mirror to a 3 disk 100 GB root pool mirror w/ a 1.6 TB RAIDZ1 pool for /export.  A bootable RAIDZ disk set.  I plan to repeat the process for an OI install and write it up for the wiki.  I just wish we had EFI boot so one could use disks over 2 TB this way.

Have Fun!
Reg


--------------------------------------------
On Tue, 4/1/14, Stefan Müller-Wilken <stefan.mueller-wilken at acando.de> wrote:

 Subject: Re: [OpenIndiana-discuss] Destroying a zombie pool
 To: "Discussion list for OpenIndiana" <openindiana-discuss at openindiana.org>
 Date: Tuesday, April 1, 2014, 2:51 AM
 
 Hi Reg,
 
 as this matter does not really accept failure: could you
 share the whole 'dd' command line? Experimenting on raw
 devices with dd can ruin your day too easily... ;-)
 
 Cheers
  Stefan