Here's the problem in a nutshell:
One samba-server (stand alone) A couple of Windows XP (sp2) clients All connected through a gigabit network
Transfers between two of the windows computers works just fine and the speed is about 20-30MB/s.
Transfers from the server to any windows computer also works fine and has the same speed.
Transfers TO the server from any windows computer is horribly slow (under 1MB/s).
BUT if a try to unpack a rar-file using winrar directly to the server the transfer speed is the "normal" 20-30MB/s.
The specifics:
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I've used the word "upload" as transfering a file from a windows client to smb-server. And "download" is the opposite of course.
Samba server:
Athlon 64 with 1,5 gig of ram. The problem occurs with both slackware 10, default install (32bit) and with a 64-bits compile of gentoo. I've also tested with slackwares precompiled samba-package (3.0.4), compiling the soure 3.0.7 under both slackware and 64-bit gentoo. But the upload speed is consistent.
Clients: Barton 2500+ and better. 512Mb ram or more.
Network:
Gigabit copper. There's no other problem with the network. No packet errors or other to indicate any hardware trouble. Testing to run nfs from a linux-client against the samba-server gives a transfer speed (in both directions) of 40MB/s.
What I've tried so far:
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When the problem occurs, ie. uploading a file to the server, none of the cpus are working more than 2-3%. There's no strange output in the samba logfiles or any indication of network troubles (like collisions, packet errors and so on).
I dumped a download and an upload with tcpdump and looked at it with ethereal. But i couldn't see anything strange except one thing. I know too little about the smb-protocoll to dicide whether the logs indicate a problem or not but they are included at the bottom in case anyone has any suggestions.
I have also tried a lot of configuration options. Including default configuration, sendfile on/off, and a bunch of different protocoll and tuning options. But it doesn't seem to make any difference, at least not for the upload speed.
Uploading multiple files in parallell helps a little but the total upload speed never goes above 3MB/s.
To exclude some of the hardware on the server I have also tried uploading files to a ram-disk (using ramfs) but it didn't change anything but the download speed.
TCPdump files
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I only exported a litte piece of the transfer. If there's something missing let me know.
http://www.ludd.ltu.se/~imz/upload.txt
http://www.ludd.ltu.se/~imz/download.txt
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