read/write multiplexed support

Marcel Müller samba at
Tue May 26 19:38:09 GMT 2009

Volker Lendecke wrote:
> On Sat, May 16, 2009 at 06:17:45PM +0200, Marcel Müller wrote:
>> Done. See
> Thanks for those. If possible, can you catch the WriteMPX
> against Windows? Maybe we're not sending the right error
> code?

Unfortunately I have no Windows at home.

But further analysis showed that OS/2 chooses sometimes Read/Write RAW
and sometimes Read/Write MPX at the connection setup.
The issue might be quite old without much noticeable effect, since Samba
3.0.x supported at least Write MPX by default and obviously no windows
server will ever accept the MPX modes over TCPBEUI. Samba 3.2.x only
made the problem to show up.

Most likely there is some kind of issue during the negotiation. Maybe
samba returns some wrong error code that made the client to choose the
MPX modes, maybe something else.
However, there seems to be a much easier solution. Since I disabled the
MPX modes in the requester configuration, I was no longer be able to
reproduce the problem. OS/2 now always uses the Read/Write RAW modes,
that provide similar performance than the multiplexed mode.
There should be no significant drawback for the same reasons why the
multiplexed modes are not essential to samba anymore. Ok the multiplexed
modes might be slightly more responsive, because other commands can be
sent while a package is transferred.


Disable the MPX modes in the requester configuration:

In bootdrive:\IBMLAN\IBMLAN.INI reset bit 14 and 15 in the wrkheuristics
setting (requires restart of the requester)

;                           1         2         3         4
;                 012345678901234567890123456789012345678901
; wrkheuristics = 1111111121311111110001011120111221001111100
;                               ^^  (old)
   wrkheuristics = 1111111121311100110001011120111221001111100
;                               ^^  (new)


More information about the samba-technical mailing list