Slow Samba performance

Riddoch, John E SITI-ITDSEP3 John.E.Riddoch at is.shell.com
Fri Oct 4 08:21:06 EDT 2002


I've been working at testing our Samba server's performance compared to a
Windows 2000 server and we're having some issues.  The primary problem is
that when saving a project from one application, it takes 2 seconds on the
Win2k server, it takes 10 seconds (or more!) via Samba.

I've done a truss -D to track how long syscalls are taking, and I've noticed
the following appearing a few times:
 0.0110 send(8, "\0\0\0 #FF S M B 201\002".., 39, 0)    = 39
i.e it's taking > .01 seconds to send 39 bytes out of a gigabit ethernet
connection, to a 100Mbit connection on the client.

What I think _might_ be happening is that Solaris might be waiting for more
data, to try and avoid sending small packets to the client; after .01
seconds, it stops waiting and sends the small packet anyway.  Is there any
way to disable this?  I'm pretty certain this isn't related to the TCP
slow/fast startup, as the TCP connection has already been created.

Any pointers on speeding this up would be appreciated.

NB: the data is held on an NFS server (running AIX) and the bottleneck may
be in that; I haven't had a chance to test using local disk as yet as a
comparison.  In any case, I still think it's ludicrous that it should take a
hundredth of a second to send 39 bytes.

Note on hardware:
Samba is running on V880 with onboard Gbit ethernet, 4 750MHz CPUs & 8GB.
Solaris 8.
Windows client is Windows 2000, SP2

Summary as usual.



John Riddoch
Unix Project Engineer
Shell Information Technology International Limited
Loirston House, Wellington Road, Altens, Aberdeen AB12 3BH

Tel: +44(0)1224 21 7660 Fax: 7502
Email: John.E.Riddoch at is.shell.com
Internet: http://www.shell.com



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