Slow network with F13 [SOLVED]

john wendel jwendel10 at
Sun Aug 22 00:16:37 UTC 2010

On 08/21/2010 12:52 PM, Bill Davidsen wrote:
> john wendel wrote:
>> I've got a couple of boxes connected with wire and a gigabit ethernet
>> switch. With F11 on the sending and receiving sides, I see a transfer
>> speed of ~ 40 MB/s transfering large files.  With F13 on the sending box
>> (same box, just new software), I get a transfer speed of ~ 23 MB/s with
>> the same files. The disk read speed on the F13 box looks to be ~ 75
>> MB/s, so it doesn't seem to be the bottleneck.
>> I'm not sure where to start looking. Any help will be much appreciated.
> Since you only changed the OS at the sending end, that lets out a slowing of
> disk write on the receiver. Since you have tested the speed of disk reads and
> found it adequate, it's likely that the issue is the network code on the sending
> end.
> However... do check the speed of reading that particular file. Remember that
> different parts of the disk are faster than others, even on Linux files
> fragment, etc. The easy way to do this is:
>     dd if=my.file of=/dev/null
> and dd will report the speed. You can see as much as 50% slower on inner tracts,
> so it's at least a possibility.

Thanks for the help. Looks like the network speed is fine, the slowdown 
appears to be in "scp", which is how I was sending the files.

Using ttcp the test the network speed, gives the following,

> 8192000000 bytes in 69.96 real seconds = 114350.28 KB/sec

Using ttcp to send one of the files gives the following result,

> 1464370115 bytes in 18.84 real seconds = 75923.92 KB/sec,

which is similar (a little faster) to the speed I see with scp in F11.

F13 scp gives me 23.3 MB/s for the same file.

Looks like I'll spend a little time poking at F13 scp and see if I can 
improve the transfer speed.

Thanks for all your help.


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