[Samba] gencache.tdb growing and growing and...

[Timur I. Bakeyev]

Hi, Peter!

I'm curious do you use stock FreeBSD with the self-compiled Samba or some
FreeBSD-based appliance? As Samba 4.7 port did hit the ports collections
only recently and comes with various extra patches.

With regards,
Timur Bakeyev.

On Mon, Dec 4, 2017 at 5:46 PM, Peter Eriksson via samba <
samba at lists.samba.org> wrote:

> Is it normal that the gencache.tdb should grow and grow “forever” and fill
> up with “RA/<hex>” posts?
>
> I’ve been investigating why our Samba 4.7.3 servers (happened with older
> version 4 servers too) would use such insane amounts of memory on our
> FreeBSD 11.1 servers (we see smbd processes using hundreds of megabytes of
> RAM and up to 5GB virtual memory).
>
> Anyway, one part that seems to use over 100MB of memory is the (shared)
> gencache.tdb database. So I looked at what was stored inside gencache.tdb
> on of the busy servers and noticed that it contained:
>
> > # tdbtool gencache.tdb check
> > Database integrity is OK and has 495309 records
>
> > # tdbtool gencache.tdb keys | egrep IDMAP/ | wc -l
> >    88974
> > # tdbtool gencache.tdb keys | egrep RA/ | wc -l
> >   406311
>
> (The number of IDMAP records I sort of can understand - our AD server
> contains some 100k users). But 406k RA records?
>
> > # tdbtool gencache.tdb dump | egrep -A4 RA/ | sed -e 's:/: :' | awk '($1
> == "[000]") {print $20}'|sort|uniq -c
> > 2001 OSX
> > 374245 Sam
> > 30080 Vis
>
> (“VIs” = Vista, “Sam” = Samba). 374245 “Samba” records seems a bit
> excessive. Our servers are mostly serving Windows 7 and Windows 10 clients.
> The most active “Samba” clients should be our Nagios monitoring system...
>
> I deleted the gencache.tdb on a test server and restarted Samba, and it
> starts out low and then slowly keeps on growing. The only client that
> connects is the monitoring system.
>
> An “RA” records leak or is this by design and every new client connection
> gets a new record?
>
> In source3/lib/util.c there is a "#define RA_CACHE_TTL 7*24*3600” - a
> week, but are the keys really removed at all? Due to the huge smbd
> processes we started restarting the Samba processes every night, could this
> prevent any kind of garbage collection routine from running?
>
> —
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