dbcopy on Linux hangs

SLES 10.3

/opt/novell/groupwise/agents/bin/dbcopy -t 6 -k /media/nss/GW/grpwise/mypo
/mnt/qnap-m-01/backup/mypo

/mnt/qnap-m-01 is CIFS share on Qnap TS-1679U0RP

mypo is ~ 100Gb

dbcopy starts, copies upto 10Gb