Some files differ between a master PFS and its mirror

[Andrea]

Hi! I'm struggling with this problem for a few days, I home someone has 
some suggestions.

On 4.8-RELEASE I have:

- A master PFS '/home/pfs/readonly' mounted as '/home/readonly' (despite 
the name it's not mounted read-only at the moment)
- Its slave PFS '/mhome/pfs/readonly' which is not mounted so I access 
it directly via /mhome/pfs/readonly

I synchronize master and slave with the command:
# hammer mirror-copy /home/readonly /mhome/pfs/readonly

But some files in the mirror are different; they have the same size in 
bytes, but different content (as shown by diff or by checksumming them); 
If try to open a jpg the display utility errors out:
display: Not a JPEG file: starts with 0x00 0x00
while the original image in the master PFS is displayed correctly.

The files showing this behavior are grouped in directories. In other 
words, some directories in the problematic PFS are mirrored without 
problems. Other directories have all their files mirrored incorrectly.

Another info: if I make a copy of the problematic directories in the 
same PFS they are mirrored correctly.

Does anybody know how can I diagnose the problem further?

King regards,
Andrea