Big amount of data transferring with slow data rate between DC (10G)

Hi guys, I'm wondering about situation with throughput between two data centers. Infrastructure looks like below: server1-(1g)SW2(10g)-SW1(10g)-----20kilometers DWDM----SW1(10g)-(10g)SW2(1g)-sever2 When I'm testing throughput between servers byiperf tcp/udp I can to achieve pretty good amount of data per seconds but when I'm trying copy files via rcp or scp for example, it sucks. Our sys tech team last times complain that they coudn't copy backup from one server to another and they have created ticket. How can I proof that everything is ok with the network or where should I looking for problem?

iperf -c 10.131.2.132 -u -b 200M -l 64 -t 10 -P 5 ------------------------------------------------------------ Client connecting to 10.131.2.132, UDP port 5001 Sending 64 byte datagrams UDP buffer size: 122 KByte (default) ------------------------------------------------------------ [ 5] local 10.131.2.131 port 50497 connected with 10.131.2.132 port 5001 [ 7] local 10.131.2.131 port 46880 connected with 10.131.2.132 port 5001 [ 6] local 10.131.2.131 port 33046 connected with 10.131.2.132 port 5001 [ 4] local 10.131.2.131 port 54935 connected with 10.131.2.132 port 5001 [ 3] local 10.131.2.131 port 37081 connected with 10.131.2.132 port 5001 [ ID] Interval Transfer Bandwidth [ 5] 0.0-10.0 sec 64.1 MBytes 53.8 Mbits/sec [ 5] Sent 1050199 datagrams [ 7] 0.0-10.0 sec 64.1 MBytes 53.8 Mbits/sec [ 7] Sent 1050190 datagrams [ 6] 0.0-10.0 sec 65.5 MBytes 54.9 Mbits/sec [ 6] Sent 1072385 datagrams [ 4] 0.0-10.0 sec 63.4 MBytes 53.2 Mbits/sec [ 4] Sent 1038869 datagrams [ 3] 0.0-10.0 sec 65.0 MBytes 54.5 Mbits/sec [ 3] Sent 1064935 datagrams [SUM] 0.0-10.0 sec 322 MBytes 270 Mbits/sec [ 4] Server Report: [ 4] 0.0-10.0 sec 29.2 MBytes 24.5 Mbits/sec 0.011 ms 560153/1038868 (54%) [ 4] 0.0-10.0 sec 54 datagrams received out-of-order [ 7] Server Report: [ 7] 0.0-10.0 sec 29.8 MBytes 25.0 Mbits/sec 0.210 ms 562634/1050189 (54%) [ 7] 0.0-10.0 sec 9 datagrams received out-of-order [ 6] Server Report: [ 6] 0.0-10.0 sec 30.5 MBytes 25.6 Mbits/sec 0.230 ms 572333/1072384 (53%) [ 6] 0.0-10.0 sec 1 datagrams received out-of-order [ 5] Server Report: [ 5] 0.0-10.0 sec 30.1 MBytes 25.2 Mbits/sec 0.171 ms 557419/1050198 (53%) [ 5] 0.0-10.0 sec 1 datagrams received out-of-order [ 3] Server Report: [ 3] 0.0-10.2 sec 30.2 MBytes 24.7 Mbits/sec 15.355 ms 570181/1064842 (54%) [ 3] 0.0-10.2 sec 1 datagrams received out-of-order iperf -c 10.131.2.132 ------------------------------------------------------------ Client connecting to 10.131.2.132, TCP port 5001 TCP window size: 16.0 KByte (default) ------------------------------------------------------------ 3] local 10.131.2.131 port 32911 connected with 10.131.2.132 port 5001 ID] Interval Transfer Bandwidth 3] 0.0-10.0 sec 1.09 GBytes 938 Mbits/sec rcp 10.131.2.132:/mnt/test5gb ~/ test5gb 100% 5120MB 13.5MB/s 06:18 scp 10.131.2.132:/home/users/user/test256mb ~/ test256mb 100% 256MB 28.4MB/s 00:09