Spontaneous development of supremely large files on different ext3 filesystems

[Andreas Dilger]

On Sep 11, 2007  17:01 -0700, Stephen Samuel wrote:
> One simple point:
> bash-3.2$bc -ql
> obase=16
> 35184386120704; 14032896
> 200000D61C00
> D62000
> 18014398562775391; 53297152
> 400000032D315F
> 32D4000
> 
> The filesize is basically the same, except for the addition of a stray
> bit, way off in left field.

Yes, it looks like single-bit corruption of some kind.

> (( Note that  both of the 'old' file sizes are multiples of 8K ))

That is because e2fsck doesn't know the correct size, so just uses
the end of the last valid block (it isn't possible to have a "hole"
at the end of the file).
 
> On 9/10/07, Maurice Volaski <mvolaski at aecom.yu.edu> wrote:
> > I have come across two files, essentially untouched in years, on two
> > different ext3 filesystems on the same server, Gentoo AMD 64-bit with
> > kernel 2.6.22 and fsck version 1.40.2 currently, spontaneously
> > becoming supremely large:
> >
> > Filesystem one
> > Inode 16257874, i_size is 18014398562775391, should be 53297152
> >
> > Filesystem two
> > Inode 2121855, i_size is 35184386120704, should be 14032896.
> >
> > Both were discovered during an ordinary backup operation (via EMC
> > Insiginia's Retrospect Linux client).
> >
> > The backup runs daily and so one day, one file must have grew
> > spontaneously to this size and then on another day, it happened to
> > the second file, which is on a second filesystem. The backup attempt
> > generated repeated errors:
> >
> > EXT3-fs warning (device dm-2): ext3_block_to_path: block > big
> >
> > Both filesystems are running on different logical volumes, but
> > underlying that is are drbd network raid devices and underlying that
> > is a RAID 6-based SATA disk array.
> > --
> >
> > Maurice Volaski, mvolaski at aecom.yu.edu
> > Computing Support, Rose F. Kennedy Center
> > Albert Einstein College of Medicine of Yeshiva University
> >
> > _______________________________________________
> > Ext3-users mailing list
> > Ext3-users at redhat.com
> > https://www.redhat.com/mailman/listinfo/ext3-users
> >
> 
> 
> -- 
> Stephen Samuel http://www.bcgreen.com
> 778-861-7641
> 
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Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.