DBCopy fails to copy all of offiles

Following our recent upgrade to GW12.0.2, our nightly DBCopy jobs aren't copying all of the contents of the offiles directories. We use DBcopy to copy our GW system to other OES11 SLES11.1 servers, where they are then backed up offline.

We are getting errors like the following in our dbcopy logfiles:

[272] Error: Failed to read next file in /root/F/PO06/offiles/fd15 rc=(8200) errno(4)
[272] Error: Error 8200 in performing CopyDirectory /root/F/PO06/offiles/fd15
or
* An error occured during copy rc(8200) errno(4) prev copied size (0) *
[096] Error: Return Code (8200) processing /root/F/PO06/offiles/fd13/3c4c410b.000
[096] Error: Failed to read next file in /root/F/PO06/offiles/fd13 rc=(8200) errno(4)
[096] Error: Error 8200 in performing CopyDirectory /root/F/PO06/offiles/fd13

If I then re-run the job, some more data is copied into offiles directory and there are less errors mentioned in the dbcopy logfile but on a relatively small PO, it took 10+ runs for the whole directory to be copied over and for the size of offiles in the copied area to match that in live.

This has specifically happened since our upgrade from GW8.0.2 to GW12.0.2. Has anyone else come across this/come up with a resolution?

Thanks