A backup using dump command over nfs takes much time to complete.

Issue

A backup using dump command over nfs takes much time to complete.

i.e)

# mount -t nfs <NFS_Server>:/export/test /nfstest

# time dump -0uf /nfstest/test.img /dev/sdb2
DUMP: Date of this level 0 dump: Tue Mar 18 14:05:44 2014
DUMP: Dumping /dev/sdb2 (/home/test/case) to /nfstest/test.img
./snip/
DUMP: finished in 339 seconds, throughput 3457 kBytes/sec
DUMP: Date of this level 0 dump: Tue Mar 18 14:05:44 2014
DUMP: Date this dump completed:  Tue Mar 18 14:11:31 2014
DUMP: Average transfer rate: 3387 kB/s
DUMP: DUMP IS DONE

real    5m47.070s
user    0m1.247s
sys 0m10.451s