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

Howard, Stewart Jameson
2015-10-20T16:07:37Z

Hi Volker and Jeremy,

Thanks for looking at my thread  :)

It looks like we're running version 1.2.10-1 of libtdb:

"""
[root@<HOST> bin]# rpm -qa|grep -i libtdb
libtdb-1.2.10-1.el6.x86_64
"""

As for Samba, we're running the Sernet distribution at version 4.1.6-7:

"""
[root@<HOST> bin]# rpm -qa|grep -i samba
sernet-samba-libs-4.1.6-7.el6.x86_64
sernet-samba-debuginfo-4.1.6-7.el6.x86_64
sernet-samba-ad-4.1.6-7.el6.x86_64
sernet-samba-client-4.1.6-7.el6.x86_64
sernet-samba-libsmbclient-devel-4.1.6-7.el6.x86_64
sernet-samba-common-4.1.6-7.el6.x86_64
sernet-samba-4.1.6-7.el6.x86_64
sernet-samba-libwbclient-devel-4.1.6-7.el6.x86_64
sernet-samba-winbind-4.1.6-7.el6.x86_64
sernet-samba-libsmbclient0-4.1.6-7.el6.x86_64
"""

I think Jeremy asked if I have a copy of the old, corrupted
gencache_notrans.tdb.  I do have the file, but I will have to check on the
possibility of posting it, since it contains domain SIDs internal to our
organization.  Also, the size of the file is ~4G, which is over the limit that
our mail servers will handle.  If it turns out that I'm able to provide the
file, we might have to find some alternative way for me to post it.  In the
meantime, is there any analysis of this file that you guys (or anyone else) can
suggest to hunt for clues as to the cause?

Thank you so much for all of your help!!

Stewart
________________________________________
From: Volker Lendecke <Volker.Lendecke at SerNet.DE>
Sent: Sunday, October 18, 2015 4:24 AM
To: Howard, Stewart Jameson
Cc: Jeremy Allison; samba at lists.samba.org
Subject: Re: [Samba] Problems with TDBs on CTDB-managed Samba instance

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

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