[Samba] Very slow transfers to Samba on Ubuntu

Raghu A raghua1111+nabble at gmail.com
Wed Jun 24 20:29:06 GMT 2009

I tried TCP_NODELAY and it didn't make a difference. I haven't tried
SO_SNDBUF and RCVBUF, but I will. As the tcpdump shows there is lot of tcp
window left.

It is not just the server since linux samba client behaves much better. What
determines SMB packet size?

What is the throughput you get? Is this with an XP/windows client?


John Du-4 wrote:
> Have you looked at adjusting the "socket options" parameter in smb.conf?
> I use "socket options = TCP_NODELAY SO_SNDBUF=8192 SO_RCVBUF=8192" in my 
> smb.conf and scp and samba take about the same amount of time to 
> transfer files from Windows to the samba server.
> Raghu A wrote:
>> There is no disk or CPU bottleneck or virus checking (server is latest
>> ubuntu). scp at the same time as this transfer can write 3-4 faster to
>> the
>> same partition. This is an Atom processor but there is more cpu left.
>> To be more specific:
>> Why does XP send only 1KB at a time to the server? I think this is pretty
>> much the culprit. I can send decoded TCP dump of initial SMB handshake if
>> you are interested. There seems to be some configuration mismatch.
>> When I tried a Ubuntu samba client it sends 4KB SMB packets. This helps a
>> lot with the transfer rate. Btw, looks like most of the CPU consumed by
>> smbd
>> is per packet.. so inceasing this packet size reduces CPU as well.
>> Raghu.
>> Ben Tyger wrote:
>>> What type of file processors are you running along with samba?. Are you
>>> running the virus checking plugin or VFS(recycle bin)? Virus checking is
>>> very cpu and disk I/O intensive these can really slow down a samba
>>> server. I can't expect VFS is all that cheap either when moving big
>>> files.
>>> Raghu A wrote:
>>>>> I mounted a samba volume on XP. XP and Ubuntu are connected over
>>>>> 100Mbps
>>>>> ethernet (router).
>>>>> I am writing a 4GB file from XP to Ubuntu and the transfer is
>>>>> extremely
>>>>> slow : only around 1-1.5 MB/s.
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