Thread (12 messages) 12 messages, 4 authors, 2012-02-07

Re: Placing the root partition on an XFS filesystem is not supported

From: Marcos Mello <hidden>
Date: 2012-02-06 10:44:29

Eric Sandeen <sandeen <at> sandeen.net> writes:
On 2/5/12 7:54 PM, Dave Chinner wrote:
quoted
On Sun, Feb 05, 2012 at 06:13:28PM -0600, Eric Sandeen wrote:
quoted
On 2/5/12 6:11 PM, Dave Chinner wrote:
<snip>
quoted
quoted
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
http://xfs.org/index.php/XFS_FAQ#Q:_Does_GRUB_work_with_XFS.3F

Eric, landed recently in util-linux's libblkid a function for that AFAIK
http://git.kernel.org/?p=utils/util-linux/util-linux.git;a=commitdiff;h=2b89be6c802bdbdf6830dbd060c96e33f179b135

Marcos

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