[Samba] Re: Horrible write performance from XP to Samba

[Peter Daum]

maybe some people would be adventurous enough to just try it out:
- Create a 1Gb file on a Samba server
  (dd if=/dev/zero of=1gm.tmp bs=1024k count=1024)
- Use a windows client to copy the file to a local disk and measure
  the time it takes to transfer the data
- copy the file back to a share on the Samba server and again
   measure the time
- post your results here

I assume that some more people would notice a problem somewhere ...

Regards,
                                 Peter Daum

Peter Daum wrote:
> I noted an extremely poor performance when copying big files from
> a windows xp client to a samba share. The exact version of samba
> does not seem to matter: I tried several different samba servers
> with versions between 3.014 and 3.0.23b running on Linux 2.4.32
> and 2.6.17 (machines and network otherwise idle, clients connected
> via fast ethernet, servers via Gbit; network performance in both
> directions around 95 Mbit/s). I made several tests copying a 1GB
> file with Windows 98 and Windows XP clients. Reading the file from
> the server takes predictably around 105 seconds (~9.75 MB/s).
> 
> Writing to the server takes only slightly longer on Win98 (130
> seconds, ~8 MB/s) while the same takes approximately 45 minutes
> from a XP client (I don't know whether this matters, I noted that
> on the XP write test, the directory listing on the server
> immediately shows a file with the final size - obviously a sparse
> file, repeatedly invoking du shows the gradually increasing actual
> size).
> 
> I wrote a little test program that just writes data to a file and
> shows the throughput; the transfer rates I get that way are pretty
> reasonable, so it is not a general problem but something that only
> occurs on specific operations like copying.
> 
> Tracing the network traffic also didn't tell me what the problem
> might be: XP uses for copying as well as for other write
> operations WriteAndXRequest, the only peculiarity I noticed is the
> slightly exotic block size of 61440 bytes per request when copying
> (which also doesn't seem to be the problem - Win98 uses the same
> block size with WriteRaw)
> 
> Has anybody else made similar experiences? (Since I could see this
> issue with differently configured servers/clients, it should not
> be just my personal problem. Of course in most settings where the
> data usually goes mostly from the server to the client it is not
> obvious)
> 
> Any ideas what's going on and what to do about it?