Q: xfs_db: invalid numrecs (*) in bmapbtd block

[Dave Chinner]

On Sun, Jun 28, 2015 at 09:44:20PM +0300, Timofey Titovets wrote:
> Good time of day list,
> i do regular check fragmentation on my servers and xfs_db show strange erros:
> 
> # xfs_db -c frag -r /dev/sdc1
> invalid numrecs (51914) in bmapbtd block

That's expected behaviour if you are running that on a mounted
filesystem. I'm assuming this is the case because you are telling
xfs_db to run in read only mode...

Why? Because an actively modified filesystem is only coherent on
disk when you consider all the modifications staged in the journal,
and xfs_db ignores the journal. Hence what it reads of disk is not
coherent and hence is not guaranteed valid.

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com