samba - Jul 2006 - Must restart Samba regularly because saving files stops working

One of our sites is currently testing Samba 3.0.21c as PDC on HP-UX
11.00 with openldap backend.
>From time to time - about every two days - it suddenly becomes
impossible for the clients (NT4 & XP) to save any more files to the
samba shares. When the problems start occurring they simply stop and
restart samba, and then everything works again for a couple of days.
Please not that the samba processes were NOT crashed; they were still
running.

Odd thing is that creating stupid little files from a Windows command
prompt - e.g. "echo SomeText > SomeFileOnASambaShare" - does
continue
to work, but saving files (even small ones) in for instance MS Word
does not work.

There are no disk space problems.
I saw no problems in syslog.

The HP-UX server does seem somewhat low on system RAM. COULD THIS
EXPLAIN SUCH PROBLEMS?
OTHER IDEAS?

Below are some extracts from log.smbd (debug level 2). I cleaned out
all irrelevant messages, and left only the "real" error messages. I
SUSPECT that the problems occur at about the same time as "the
_net_sam_logon: creds_server_step failed. Rejecting auth request "
messages, but for now I'm not sure about that at all.

---------------------------- extracts from log.smbd
----------------------------
[2006/07/17 07:35:39, 2] smbd/sesssetup.c:(772)
  setup_new_vc_session: New VC == 0, if NT4.x compatible we would close all old
resources.
  guest user (from session setup) not permitted to access this share (programs)
  open_sockets_smbd: accept: No buffer space available

[2006/07/17 08:34:05, 2] libsmb/credentials.c:(159)
  creds_server_check: credentials check failed.
[2006/07/17 08:34:05, 2] rpc_server/srv_netlog_nt.c:(665)
  _net_sam_logon: creds_server_step failed. Rejecting auth request
from client VOEREN12 machine account VOEREN12$

[2006/07/17 08:37:11, 2] auth/auth.c:(315)
  check_ntlm_password:  Authentication for user [administrator] ->
[administrato
r] FAILED with error NT_STATUS_NO_SUCH_USER
[2006/07/17 08:37:21, 2] auth/auth.c:(315)
  check_ntlm_password:  Authentication for user [administrator] ->
[administrato
r] FAILED with error NT_STATUS_NO_SUCH_USER
  open_sockets_smbd: accept: No buffer space available

[2006/07/17 08:37:38, 2] rpc_server/srv_samr_nt.c:(2670)
  Returning domain sid for domain VOEREN_DOM ->
S-1-5-21-406224505-1568694035-11
63074499
  guest user (from session setup) not permitted to access this share (programs)

[2006/07/17 08:48:50, 0] lib/util_sock.c:(528)
  read_data: read failure for 4 bytes to client 14.42.47.113. Error = Connection
 timed out

[2006/07/17 09:22:49, 0] lib/util_sock.c:(528)
  read_data: read failure for 4 bytes to client 14.42.47.112. Error = Connection
 timed out
[2006/07/17 09:22:50, 0] lib/util_sock.c:(528)
  read_data: read failure for 4 bytes to client 14.42.47.112. Error = Connection
 timed out
[2006/07/17 09:22:56, 0] lib/util_sock.c:(528)
  read_data: read failure for 4 bytes to client 14.42.47.112. Error = Connection
 timed out

[2006/07/17 09:56:37, 2] rpc_server/srv_samr_nt.c:(2670)
  Returning domain sid for domain VOEREN_DOM ->
S-1-5-21-406224505-1568694035-11
63074499
--------------------------------------------------------

On Wed, Jul 19, 2006 at 04:35:54PM +0200, Roel Slegers
wrote:
> The HP-UX server does seem somewhat low on system RAM. COULD THIS
> EXPLAIN SUCH PROBLEMS?
> OTHER IDEAS?
In lower case: This 

open_sockets_smbd: accept: No buffer space available

is a message from the kernel that points at extreme kernel
memory problems. You should really either put more RAM into
that box or otherwise tune your TCP parameters.

Volker
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On 2006/7/19, Volker Lendecke <Volker.Lendecke@sernet.de>
wrote:
> On Wed, Jul 19, 2006 at 06:42:30PM +0200, Roel Slegers wrote:
> > When you say "tuning tcp parameters" could you point me in
the right
> > direction please? Are you talking about tuning the HP-UX kernel, or
>
> This would be the kernel first. smb.conf does not do
> anything here. But I don't know enough about HP/UX to how to
> tune it. You need to give the TCP/IP more space, but to know
> what exactly needs tuning I can't tell from here.
>
> Volker
>
Thanks Volker,
We'll see what we can find in our kernel parameters.

Roel

PS: Sorry but I forgot to send a copy of my previous message to the
samba list, so I include that now:

>> On Wed, Jul 19..., Roel Slegers wrote:
>> Hi, and thanks.
>>
>> That "No buffer space available" message is something
we've always had
>> on our test servers, also on servers with plenty of RAM running only
>> samba with maybe 1 or 2 pc's connected. And this with the various
>> samba versions (2.x - 3.x) we've experimented with in the past.
>> So IMHO I do not think this is RAM related. But to make sure we should
>> maybe resolve this before looking any further.
>> When you say "tuning tcp parameters" could you point me in
the right
>> direction please? Are you talking about tuning the HP-UX kernel, or
>> about tuning smb.conf? Do you know of some documentation that can help
>> do this?
>>
>> BTW googling seems to show that this "No buffer space
available"
>> especially occurs a lot on HP-UX 11 servers; is that possible?
>>
>> PS: sorry for the upper case...