Eric Sandeen <sandeen <at> sandeen.net> writes:
> On 2/5/12 7:54 PM, Dave Chinner wrote:
> > On Sun, Feb 05, 2012 at 06:13:28PM -0600, Eric Sandeen wrote:
> >> On 2/5/12 6:11 PM, Dave Chinner wrote:
> >> well, it was worse than that. I can work around the grub-on-a-partition
> >> problem, but what I ran into was grub reading & writing to/from the block
> >> device under a mounted filesystem - corruption and hilarity ensued.
> > Oh, grub2 does worse things than that - grub_probe mounts any device
> > that appears to have a valid superblock so it can find out what
> > devices it needs to list in it's boot menu. I found this out when I
> > built a big DM stripe out of disks that used to have filesystems on
> > them. grub-probe mounted every single device -inside- the stripe
> > and ran log recovery on them, corrupting the new filesystem and
> > quite a bit of data on the DM stripe they were part of....
> Ok, your horror story wins from a pain POV ;)
> but sounds like someone should have zeroed out a bit more disk
> when setting up the dm stripes :(
> I've always thought maybe we needed a libzero.so to zap every known signature
> on disk....
Thanks a lot for the explanation folks! It would be nice have this documented on
the XFS FAQ
Eric, landed recently in util-linux's libblkid a function for that AFAIK