[Samba] Problems with TDBs on CTDB-managed Samba instance

[Volker Lendecke]

On Sat, Oct 17, 2015 at 04:13:30PM +0000, Howard, Stewart Jameson wrote:
> gencache_notrans.tdb
> gencache.tdb
> mutex.tdb

Just a side-remark: These tdbs have nothing to do with ctdb,
they are purely local.

> Because of the current steady size of this file compared
> to its repeated, intermittent, and rapid inflation, we
> suspect that there is some operational condition which
> *causes* the corruption and which we're running into with
> some regularity.  Our cluster is attached to a rather
> large ADS domain and `strings gencache_notrans.tdb|less`
> during the trouble reveals a long series of Windows SID
> entries followed eventually by a *very large* number of
> the ASCII character "B" (presumably going all the way to
> the end of the file.  Our current suspicion in that there
> is some ADS user whose record, when ingested, somehow
> corrupts the TDB.  Our investigations into the last
> *successfully-ingested* SID in the corrupt TDB will
> continue on Monday morning.

We should never go beyond a few MBs for
gencache_notrans.tdb.

What version of Samba are you running, in particular what
version of tdb? There have been significant improvements in
tdb's freelist handling that should keep tdbs a lot smaller.
These changes came with Samba 4.2.

Volker

-- 
SerNet GmbH, Bahnhofsallee 1b, 37081 Göttingen
phone: +49-551-370000-0, fax: +49-551-370000-9
AG Göttingen, HRB 2816, GF: Dr. Johannes Loxen
http://www.sernet.de, mailto:kontakt at sernet.de