Samba running on s390 system stops responding and needs to be restarted

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Environment

SUSE Linux Enterprise Server 11 Service Pack 3 (SLES 11 SP3)

Kernel: 3.0.93-0.8-default s390x

Product: samba-3.6.3-0.42.1 Sun Nov 3 08:00:08 2013

Situation

Samba shares become unavailable.
A LAN trace during the outage shows an NT Create AndX Request being TCP ACK'd by the server but Samba never responds.
A restart of Samba resolves the issue for a while.

Resolution

In the [global] section of the /etc/smb.conf set add the line:
use mmap = no
Save the change
Restart Samba (rcsmb restart)

Cause

The cached tdb files were being corrupted.
The restart of Samba recreated them and Samba worked until the next instance of the corruption.

Here is the mmap setting as described in the man page for the smb.conf file.

This global parameter determines if the tdb internals of Samba can depend on mmap working correctly on the running system. Samba requires a coherent mmap/read-write system memory cache. Currently only HPUX does not have such a coherent cache, and so this parameter is set to no by default on HPUX. On all other systems this parameter should be left alone. This parameter is provided to help the Samba developers track down problems with the tdb internal code.

Default: use mmap = yes

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