[Samba] Transfer rates faster than 23MBps?

[Jeremy Allison]

On Tue, Sep 19, 2006 at 06:19:43PM -0700, Mark Smith wrote:
> We use SMB to transfer large files (between 1GB and 5GB) from RedHat AS4 
> Content Storage servers to Windows clients with 6 DVD burners and 
> robotic arms and other cool gadgets.  The servers used to be Windows 
> based, but we're migrating to RedHat for a host of reasons.
> 
> Unfortunately, the RedHat Samba servers are about 2.5 times slower than 
> the Windows servers.  Windows will copy a 1GB file in about 30 seconds, 
> where as it takes about 70 to 75 seconds to copy the same file from a 
> RedHat Samba server.
> 
> I've asked Dr. Google and gotten all kinds of suggestions, most of which 
> have already been applied by RedHat to the stock Samba config.  I've 
> opened a ticket with RedHat.  They pointed out a couple errors in my 
> config, but fixing those didn't have any effect.  Some tweaking, 
> however, has gotten the transfer speed to about 50 seconds for that 1GB 
> file.
> 
> But I seem to have hit a brick wall; my fastest time ever was 44 
> seconds, but typically it's around 50.
> 
> I know it's not a problem with network or disk; if I use Apache and HTTP 
> to transfer the same file from the same server, it transfers in about 15 
> to 20 seconds.  Unfortunately, HTTP doesn't meet our other requirements 
> for random access to the file.
> 
> Do you folks use Samba for large file transfers at all?  Have you had 
> any luck speeding it up past about 23MBps (the 44 second transfer 
> speed)?  Any help you may have would be fantastic.  Thanks.

An interesting thing you could do is to use a port of smbclient
on Windows (no I don't know where to get one :-) to copy the
client to the Windows client in userspace. smbclient will use
read pipelining (ie. issue more than one read at a time) whereas
Windows clients issue one read, wait for response, issue the next
read, wait for response etc.

That would tell you if it's a client redirector issue. You could
probably use cygwin to compile smbclient.

Jeremy.