freebsd stable - Mar 2008 - Odd file in /lost+found after softupdate inconsistency in fsck

Hi all,

My server froze up tonight after a 2 month uptime running 6.3-PRERELEASE 
from Dec 28 2007.

I had to fsck /home by hand because of an inconsistency fsck couldn't 
repair automatically -- something to do with an unexpected softupdate 
inconsistency.

After that, I ended up with some files in /home/lost+found, one of which 
is quite interesting:

/home/lost+found# ls -lksh
total 24432
24432 -r--------  1 root  operator    40G Mar  5 20:12 #0000005

It is 40G in size but only occupies 24432k on disk, so it is a sparse 
file.  I'm not aware of any sparse files of quite that size on my system 
(or relative sparseness) but it's possible i might overlook one.

But the thing that's interesting to me is the inode number (inode 5) and 
the fact that rm doesn't want me to remove it:

/home/lost+found# rm \#0000005
override r--------  root/operator snapshot for #0000005? n

Is there a magic "shapshot" flag on the file?  Have I somehow damaged
my
ufs2+softupdates filesystem by losing its inode #5 containing snapshot 
data?

Any insights appreciated,
-- 
Tod McQuillin

On Wed, Mar 05, 2008 at 09:43:15PM +0900, Tod McQuillin
wrote:
>/home/lost+found# ls -lksh
>total 24432
>24432 -r--------  1 root  operator    40G Mar  5 20:12 #0000005
>
>It is 40G in size but only occupies 24432k on disk, so it is a sparse file. 
The file permissions and sparseness matches a snapshot.  If your FS
is 40GB then it is a snapshot.
>/home/lost+found# rm \#0000005
>override r--------  root/operator snapshot for #0000005? n
The file itself is not writable so rm prompts.  This is normal.
>Is there a magic "shapshot" flag on the file?  Have I somehow
damaged my
>ufs2+softupdates filesystem by losing its inode #5 containing snapshot 
>data?
No and no.  You can have multiple snapshots in a filesystem.

-- 
Peter Jeremy
Please excuse any delays as the result of my ISP's inability to implement
an MTA that is either RFC2821-compliant or matches their claimed behaviour.
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on 05/03/2008 14:43 Tod McQuillin said the following:
> Hi all,
> 
> My server froze up tonight after a 2 month uptime running 6.3-PRERELEASE 
> from Dec 28 2007.
> 
> I had to fsck /home by hand because of an inconsistency fsck couldn't 
> repair automatically -- something to do with an unexpected softupdate 
> inconsistency.
> 
> After that, I ended up with some files in /home/lost+found, one of which 
> is quite interesting:
> 
> /home/lost+found# ls -lksh
> total 24432
> 24432 -r--------  1 root  operator    40G Mar  5 20:12 #0000005
> 
> It is 40G in size but only occupies 24432k on disk, so it is a sparse 
> file.  I'm not aware of any sparse files of quite that size on my
system
> (or relative sparseness) but it's possible i might overlook one.
> 
> But the thing that's interesting to me is the inode number (inode 5)
and
> the fact that rm doesn't want me to remove it:
> 
> /home/lost+found# rm \#0000005
> override r--------  root/operator snapshot for #0000005? n
Are you sure that it doesn't want to remove it? It's just asking you the
question (maybe because you executed rm  as non-root or maybe because of
the mode of the file); you can answer 'yes', you know.
> Is there a magic "shapshot" flag on the file?  Have I somehow
damaged my
> ufs2+softupdates filesystem by losing its inode #5 containing snapshot 
> data?
> 
> Any insights appreciated,
You can try stat(1) on it to see all the details, that could help with
further conclusions.

-- 
Andriy Gapon