[Samba] Samba -> WinXP: slow transfers, partial solution

Charles Marcus CMarcus at Media-Brokers.com
Mon Apr 16 11:01:12 GMT 2007

> I'm running Samba 3.0.24 as PDC and file server on Gentoo Linux, AMD64, 
> 2.6.19 kernel, 100MBit/s network, and experience quite slow file 
> transfers from Samba to WinXP SP2 clients: the speed is varying, but is 
> about 1-2Mb/s at best.

I'm assuming for the rest of this that you mean MB/sec not Mb/sec when 
referencing transfer speeds...

>  b) Transfering to/from Samba server from Gentoo Linux on the same PC 
> where WinXP is installed (so, completely the same hardware and 
> connection) is also at normal speed.

So, you are running something in a VM?

>  c) Transferring to/from WinXP to the server where Samba is installed 
> using any other protocol (such as HTTPS or SCP) is also at normal speed.

Define 'normal'...

> 2) CPU is at almost idle level both at client and server, so it's not 
> the issue.
> 3) If there is any other network activity, transfer speed is increased 
> up to normal level: f.e. doing two simulteneous transfers from Samba 
> server to WinXP client gives 5Mb/s at each transfer, as expected.

Again, define 'normal'?

100Mb network connections should give @ 12MB/sec transfer speeds, no? So 
5MB/sec speeds are certainly not 'normal'.

> 4) Running tcpdump on server while the transfer is performed improves 
> transfer speed in about 1.5 - 3 times, but still not to the normal speed.

TCP dumps are fine, but you neglected to provide the most important 
thing for initial troubleshooting assistance: where is your config?

> 5) Playing with "socket options" does not give any results.

Modern linux kernels (2.6+) do *not* need to have these values tuned, so 
it is recommended to not set them *at* *all*. Just delete these entries.

> Specifically, using advices from the article 
> http://www.dd.iij4u.or.jp/~okuyamak/Documents/tuning.english.html about 
> SO_SNDBUF does not improve situation (but read below).

Well, since this article is dated from 2000, I don't think I'd trust it 

> 6) tcpdump + tcptrace show that there are a lot of retransmissions, see 
> dumps below.
> 7) I've tested several WinXP clients with different hardware, all with 
> the same results.

What about the NIC on the Samba server? If all clients are affected the 
same, then that is the NIC you should focus on (if it is indeed a 
hardware issue).

> 8) Samba logs looks normal to me, nothing special.
> Points (3) and (5), and also the article about SO_SNDBUF tuning gave me 
> an idea that there might be smth wrong with ACKs sent from WinXP.

I think you need to go back to square one, and start over, but with up 
to date references - like the excellent 'Samba-3 By Example' and/or 'The 
Official Samba-3 HOWTO and Reference Guide'.

> It seems that I'm not the only one who have similar problems: see BUGs 
> 2117 and 3706 in Bugzilla, and discussion at Gentoo mailing list: 
> http://forums.gentoo.org/viewtopic-p-2820556.html

This too is an old(er) thread - and it specifically mentions switching 
from smbfs to cifs as the best solution...


Best regards,


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