Data corruption should be *very* rare in any working system. The majority
of the cases occurs when two systems write on the same disk, uncoordinated.
When you changed from ext3 to ext2, you threw away the only thing
preventing this to happen. Ext3 detected something amiss, and locked the
disk to prevent further damage. ext2 don't see anything amiss, write down
the data, and corrupts everything. Working as designed. You just removed
the safety pin that blocked your gun to fire when aimed at your foot (or
your head).

You should execute DISKMAP or DIRMAP on your system to see if there are
overlapping minidisks. You should see a overlap. Correcting the overlap
shall correct the corruption.
And, please, revert back to ext3. It will save your data, and you can see
messages on syslog if things go astray...

Mauro
http://mauro.limeiratem.com - registered Linux User: 294521
Scripture is both history, and a love letter from God.


2013/10/2 Donald Russell <russell....@gmail.com>

> RHEL 5.8 zLinux on zVM 6.1 using ECKD disks
>
> We have a recurring problem where files get corrupted. It always happens in
> the same directory, and we always wind up running fsck in single user mode
> to get the file system back together.
>
> The file system is EXT-2. (We changed from EXT-3 on this FS due to numerous
> journaling errors which caused the FS to go to RO mode)
>
> In the case I'm currently working on, a ".so" file (binary) has a chunk of
> plain text in the middle of it. The "chunk" is 4K bytes long, and is a
> piece of a program listing. 4K is the block size of the underlying DASD.
>
> I am now in the process of trying to find when this happened by restoring
> backup copies and seeing if I can narrow the time frame down.
>
> Obviously I don't expect a "do this to fix the problem", but what I'm
> wondering is, has anybody else encountered this? What could cause a block
> in the middle of the file to be overwritten this way? Are there any tools I
> can run (preferably while the system is at runlevel 3 or 5) to check if two
> (or more) files are using the same block in a file?
>
> I envision a "bad block pointer" somewhere, but how does that happen?
>
> I'm considering converting the file system to EXT-4... I don't think
> there's a conversion per-se, I'd create a new EXT-4 FS then copy all the
> files from the EXT2 FS to the EXT-4 one.
>
> Any suggestions/help are greatly appreciated.
>
> Thank you,
> Donald Russell
>
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