Block bitmap differences

Roland Bock rbock at
Thu Oct 23 16:05:57 UTC 2008


thank you for your answers.

Is it normal to encounter file systems with minor errors? We run 8 
systems with Ubuntu 8.04 64bit and e2fsck reports "<device> contains 
file system with errors" for at least one partition on every machine.

Since there are 4 different types of hardware configurations, I tend to 
say that hardware is rather not to be blamed...

If it is not normal, what could be the reasons?
Are there any options to turn on logging which could give more insight 
(what would be the performance impact)?

Thanks and regards,


Theodore Tso wrote:
> On Thu, Oct 23, 2008 at 10:00:44AM +0200, Roland Bock wrote:
>> Hi,
>> a few weeks ago, an unhealthy combination of firmware in an Adaptec Raid  
>> controller and Seagate disks damaged my Raid6 filesystem. A bunch of  
>> files were damaged or lost at that time after the firmaware was updated  
>> and I had run e2fsck. Luckily, I was able to restore everything from a  
>> backup. A subsequent check with e2fsck reported no errors.
>> Yesterday, I ran e2fsck -n again, to see if the system is still OK. It  
>> isn't and I have no idea how to interpret the messages (see attachment).
> You ran the e2fsck while the filesystem is mounted.  So the output
> reported is not trustworthy, and block allocation bitmap differences
> and free block/inode accounting information being wrong is normal when
> running e2fsck -n on a mounted filesystem.  
> This message, however, is cause for concern:
>> /dev/sdb1 contains a file system with errors, check forced.
> This means the filesystem noticed some discrepancy (for example, when
> freeing a block, it noticed that the block bitmap already showed the
> block as being not in use, which should never happen and indicates
> filesystem corruption).
> I would recommend that you schedule downtime so you can run e2fsck on
> the filesystem while it is unmounted.  Given the errors that you saw
> when running e2fsck while it was mounted, it's unlikely that you will
> see anything serious, but it is still something that you should do.
> Regards,
> 							- Ted

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