[Samba] Profile loading/saving on gigabit network only runs at fast ethernet speeds! Help!

[Jonathan Bougher]

Hello everyone,

I could really use some help trying to diagnose a tricky issue within the
domain
I have set up.

I am using samba-3.0.28-1.el5_2.1 and openldap-2.3.27-8.el5_2.4 on a server
running Centos 5.1.

I have everything working properly within the domain, users can log in,
netlogon
scripts are run, their profile is loaded, etc.

I have been extremely happy with this software and can't thank the makers
enough
- great work!

The issue I am having is with the speed of profile loading/saving. This
network
is hosted on a Gigabit Lan - this is a classroom environment where students
must
save large files in their profile (virtual machines actually = ~3-4GB per
profile & will grow...).

I know the best option is to save the work elsewhere, like their mapped home
directory, but it would be highly inconvenient to copy the VM back and forth
every time they wanted to use it (although much faster than the logon/logoff
speeds).

Let me elaborate: I have done speed tests transferring files and directories
directly to writable shares. I have monitored the network speeds with iptraf
on
the server while downloading/uploading a 1 GB or file or large directory on
the
relevant interface (there are 4 local interfaces) and these are my
approximate
results:

DL from Samba Share: 300,000 - 400,000 kb/s
UPL to Samba Share: 300,000 - 400,000 kb/s

These speeds are GREAT! I was blown away! -- But then take a look at the
speeds
at which the network operates when loading/saving a user's profile while
logging
in/out:

Profile Logoff: 50,000 kb/s (a ~3GB profile takes roughly 10 min to load)
Profile Logon: Not Tested - but observed to take about 10 minutes

So my dilemma is that, while the networking is functioning exceptionally
well in
all other areas, it just takes so long to login/logoff! The users need to
have
roaming profiles (they do switch machines sometimes) & I would like them to
be
able to store a lot of data inside their profile without speed becoming too
much
of an issue like it is now.

I have messed around with a few tweaking options in the smb.conf file, but
they
have not helped so far. So, I just went back to using TCP_NODELAY. I have
turned
off oplocks as well.

I am not sure how to proceed now and I am pretty much taking random stabs in
the
dark with this issue, any help would be GREATLY appreciated!

Thank you all,

Jonathan