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I am using Ubuntu with a 2Mbps link. I would do scp to the Ubuntu cloud servers to copy a .war file which is 14MB. It used to take only 2 minutes to copy this .war file under /tmp of the cloud server. Now it takes more than 15 minutes.

While doing scp it stalls and restarts again. The scp progress looks like this:

app1.war                     15%    2320KB  61.3KB/s - stalled -^

Any tips? I'm asked to fix this soon.

The output of tcpdump -n -n host my-dest-ip and port 22 is (I just stopped it with Ctrl+C)

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
^C
0 packets captured
0 packets received by filter
0 packets dropped by kernel
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If you try to copy that file to some other server than Ubuntu cloud, is that still slow? Try to first find if it's your uplink that stalls or if Ubuntu cloud is somehow limiting you. –  Janne Pikkarainen Sep 29 '10 at 6:50
    
yes it is slow for all 3 cloud servers –  user53864 Sep 30 '10 at 8:03
    
The problem was with my ISP. Sorry! –  user53864 Dec 20 '10 at 4:25

1 Answer 1

up vote 1 down vote accepted

it would be useful to find out if anything obvious is going wrong at the network level. do you have root on either end? can you do a tcpdump to isolate the scp datastream?

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Yeah root is present. I don't have any idea of how to do tcpdump –  user53864 Sep 28 '10 at 14:46
    
on the source box, try "tcpdump -n -n host DESTINATION_BOX and port 22", replacing DESTINATION_BOX with the ip address of the destination box. i should add that by "do you have root" i mean "do you have root access", which you will need to do a tcpdump. –  MadHatter Sep 28 '10 at 15:17
    
Sorry!. As you said it would be useful to find out if anything obvious is going wrong at the network leve it was my ISP's problem. –  user53864 Jan 22 '11 at 2:19
1  
Well, four cheers for you for coming back and letting us all know! Glad it's fixed, but if I were you, I'd spend a couple of hours learning to use tcpdump in the interim; it's an extremely useful tool for diagnosing problems like this (look for retransmissions, weird ICMP grumbles, that kind of thing). –  MadHatter Jan 22 '11 at 7:53
    
I would like to copy your habits. I'll learn that. Thanks! –  user53864 Jan 23 '11 at 16:24

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