Odd behavior w/ read raw and write raw under NT1

[Peter Chen]

A coworker and I have been doing some performance tuning with Samba 20b4
under Linux 2.0.36 (RedHat 5.2 distribution) on a 100-T network.  The
protocol is NT1.  Two settings are tweaked in particular, "read raw" and
"write raw".  When both are yes, reading a large file results in 6M/s, but
writing is only 2M/s, which is far below writing to an NT server (6M/s).
If any of "read raw" or "write raw" is off, the result is the other way
around, with writing a file to be around 6M/s, and reading around 2M/s.

When I changed the protocol to LANMAN2, "read raw = yes" and "write raw =
no" result in good throughput for both reading and writing.  The only
problem is that LANMAN2 doesn't support long filenames.  So we looked at
the source searching for places where "read raw" and "write raw" are used.
To take it a step further, we downloaded the SMB protocol specs from
Microsoft.  It turned out that there are two separate bits in LANMAN2's
message for read raw and write raw, whereas under NT1, in the
"Capabilities" structure, there is only a 1 bit flag for whether the server
supports both read raw and write raw.  This seems to be exactly where the
problem is.

So how does one configure the server using protocol NT1 to have read raw =
yes, and write raw = no?  Right now the flags are simply "and" together in
the code.
TIA.

Pete <petechen at remus.rutgers.edu>

Peter Chen
email: <mailto:petechen at remus.rutgers.edu>