SCP speed question

[Alma J Wetzker]

Matthew Carpenter wrote:
> On Thursday 04 January 2007 20:51, Kurt Wall wrote:
>> On Wed, Jan 03, 2007 at 11:06:27AM -0600, Alma J Wetzker wrote:
>>> What speed should you get with scp on a 100 Mb/s backbone?  I backup my
>>> home directory with scp to my server and I am getting 3.8 MB/s.  That
>>> seems a bit slow to me.
>> I can get anywhere between 4 and 11Mb/s on my 100Mb/s router. As others
>> have pointed out, scp is slow. At work, we use dd for rough estimates
>> of throughput. There are other limiting factors, too: the speed of the
>> slowest link, the inability of the kernel or NIC driver (or both) to
>> saturate bandwidth, window scaling, the MTU, and more.
> 
> Are you sure you're not seeing between 4 and 11MB/s?  Most measurements of 
> transfer speed are done in BYTES not bits, as the network gear is rated.  
> Approx divide by 10, particularly over wan links (analog: 8 bits data, 1 
> start, 1 stop).  Or if you want to think perfect world switching, /8 is more 
> your cup o' tea.

I was pretty careful with the capital and lower case 'B' in the post.  I
almost get 4MB/s.  Thing is, The switch says it is supposed to be full
duplex, so I should have 200 Mb/s as a theoretical max speed.  I am
playing with rsync now.  Not that much different.

    -- Alma