samba - Aug 2002 - SAMBA on HP-UX specific problem: Write Delay Failures! Why?!

There seem to be problems with any SAMBA running on an HP-UX UNIX.

There are 2 available binaries (depots) for HP-UX:

samba-2.2.3a from http://hpux.connect.org.uk/ - The HP-UX Porting  Centre

and the latest

samba-2.2.5 from  http://de.samba.org/samba/ftp/Binary_Packages/hp/samba2.2.5/


The problems are:


We use SAMBA on a Databse server (HP-UX 11.11) and 4 Terminal Servers  under
WIN2000 Server  have to constantly write files to SAMBA shares.  All seems to
work fast and fine until "Delayed write errors" began to  appear on
the Terminal Servers, resulting in many files not being saved  to disk.

We had this problem with both binaries, although there was a noticeable 
improvement when we upgraded to 2.2.5. But still now and then we got  empty
files which is unacceptable for a live database.

Looking at the log files we spotted a curious error message which we  first
thought was related to the problem but later we were proven  wrong:

[2002/08/08 12:00:35, 0] lib/util_sec.c:(52)
  Failed to set uid privileges to (0,30022) now set to (30022,30022)
[2002/08/08 12:00:35, 0] lib/util.c:(2456)
  PANIC: failed to set uid

[2002/08/08 12:00:35, 0] lib/util_sec.c:(52)
  Failed to set uid privileges to (0,30022) now set to (30022,30022)
[2002/08/08 12:00:35, 0] lib/util.c:(2456)
  PANIC: failed to set uid


On our server was installed the 2.2.3a version - from source which  enabled us
to apply the following patch (by manually editing the file  below):

 /opt/samba_src/samba/source/lib/util_sec.c :


  *********************************************************************** *****/
 void restore_re_uid(void)
 {
+#ifdef USE_SETRESUID
+	setresuid(saved_ruid, saved_euid, -1);
+#else
 	set_effective_uid(0);
 	set_effective_uid(saved_euid);
 	if (getuid() != saved_ruid) setuid(saved_ruid);
 	set_effective_uid(saved_euid);
+#endif
 
 	assert_uid(saved_ruid, saved_euid);
 }

**********************************************************************


This fix came from a message by dsiebert@engineering.uiowa.edu way back  from
Dec  8 20:47:29 1999 in the samba-patches discussion forum.

But this fix is impossible when installing from the depots.

The above fix stopped the error messages but did not stop the write  delay
failures.

So why do I keep getting these write failures! The network is not  heavily
loaded, the HP-UX server is very fast (4 RISC CPUs, 4 SCSI  arrays, lots of
memory)

Have other HP-UX SAMBA users had a similar write delay problem?
I am planning to install from source the latest SAMBA. I read that for  HP-UX it
is important that compile is run with gcc not cc. Has anybody  had a successful
from source installation on HP-UX?


Please give me your hints, however remote....


Thanx!

Ivailo Chipev

Sofia Water PLC
Bulgaria

Your problem may be related to the Windows 2000 Terminal Servers.

Samba does not work well under heavy loads with Terminal Server on
Windows 2000.  Microsoft commented out the MultipleUsersOnConnection
code from their Windows 2000 redirector.  On NT 4.0 Terminal Server,
the MultipleUsersOnConnection registry parameter was used to establish
a separate VC (TCP connect) for every TS user who opened a share from
the TS to a particular Samba server.  On Windows 2000 TS - without
the MultipleUsersOnConnection registry parameter - only one TCP VC
gets established from the TS to a Samba server.  Thus, all TS users
who mount a Samba share will use the same TCP connection, and thus 
the same smbd.  If you have multiple users from one Windows 2000 TS
writing to the Samba server via one smbd, I could see how problems
might arise.

If you have access to a NT4.0 Terminal Server, you could try testing
it with the MultipleUsersOnConnection parameter enabled (see Q190162).
Also, you could try testing your DB application against the Samba
server without the Terminal Server.

Eric Roseme
Hewlett-Packard

"Chipev, Ivailo" wrote:
> 
> There seem to be problems with any SAMBA running on an HP-UX UNIX.
> 
> There are 2 available binaries (depots) for HP-UX:
> 
> samba-2.2.3a from http://hpux.connect.org.uk/ - The HP-UX Porting  Centre
> 
> and the latest
> 
> samba-2.2.5 from 
http://de.samba.org/samba/ftp/Binary_Packages/hp/samba2.2.5/
> 
> The problems are:
> 
> We use SAMBA on a Databse server (HP-UX 11.11) and 4 Terminal Servers 
under WIN2000 Server  have to constantly write files to SAMBA shares.  All seems
to work fast and fine until "Delayed write errors" began to  appear on
the Terminal Servers, resulting in many files not being saved  to disk.
> 
> We had this problem with both binaries, although there was a noticeable 
improvement when we upgraded to 2.2.5. But still now and then we got  empty
files which is unacceptable for a live database.
> 
> Looking at the log files we spotted a curious error message which we  first
thought was related to the problem but later we were proven  wrong:
> 
> [2002/08/08 12:00:35, 0] lib/util_sec.c:(52)
>   Failed to set uid privileges to (0,30022) now set to (30022,30022)
> [2002/08/08 12:00:35, 0] lib/util.c:(2456)
>   PANIC: failed to set uid
> 
> [2002/08/08 12:00:35, 0] lib/util_sec.c:(52)
>   Failed to set uid privileges to (0,30022) now set to (30022,30022)
> [2002/08/08 12:00:35, 0] lib/util.c:(2456)
>   PANIC: failed to set uid
> 
> On our server was installed the 2.2.3a version - from source which  enabled
us to apply the following patch (by manually editing the file  below):
> 
>  /opt/samba_src/samba/source/lib/util_sec.c :
> 
>   ***********************************************************************
*****/
>  void restore_re_uid(void)
>  {
> +#ifdef USE_SETRESUID
> +       setresuid(saved_ruid, saved_euid, -1);
> +#else
>         set_effective_uid(0);
>         set_effective_uid(saved_euid);
>         if (getuid() != saved_ruid) setuid(saved_ruid);
>         set_effective_uid(saved_euid);
> +#endif
> 
>         assert_uid(saved_ruid, saved_euid);
>  }
> 
> **********************************************************************
> 
> This fix came from a message by dsiebert@engineering.uiowa.edu way back 
from Dec  8 20:47:29 1999 in the samba-patches discussion forum.
> 
> But this fix is impossible when installing from the depots.
> 
> The above fix stopped the error messages but did not stop the write  delay
failures.
> 
> So why do I keep getting these write failures! The network is not  heavily
loaded, the HP-UX server is very fast (4 RISC CPUs, 4 SCSI  arrays, lots of
memory)
> 
> Have other HP-UX SAMBA users had a similar write delay problem?
> I am planning to install from source the latest SAMBA. I read that for 
HP-UX it is important that compile is run with gcc not cc. Has anybody  had a
successful from source installation on HP-UX?
> 
> Please give me your hints, however remote....
> 
> Thanx!
> 
> Ivailo Chipev
> 
> Sofia Water PLC
> Bulgaria
> --
> To unsubscribe from this list go to the following URL and read the
> instructions:  http://lists.samba.org/mailman/listinfo/samba

On Fri, Aug 23, 2002 at 09:13:49AM -0700, Eric Roseme
wrote:
> Your problem may be related to the Windows 2000 Terminal Servers.
> 
> Samba does not work well under heavy loads with Terminal Server on
> Windows 2000.  Microsoft commented out the MultipleUsersOnConnection
> code from their Windows 2000 redirector.  On NT 4.0 Terminal Server,
> the MultipleUsersOnConnection registry parameter was used to establish
> a separate VC (TCP connect) for every TS user who opened a share from
> the TS to a particular Samba server.  On Windows 2000 TS - without
> the MultipleUsersOnConnection registry parameter - only one TCP VC
> gets established from the TS to a Samba server.  Thus, all TS users
> who mount a Samba share will use the same TCP connection, and thus 
> the same smbd.  If you have multiple users from one Windows 2000 TS
> writing to the Samba server via one smbd, I could see how problems
> might arise.
A quick way around this is to use NetBIOS aliases in Samba
and get different users to connect to different Samba
names.

Jeremy.