Ability to limit memory usage for zones on an authoritative server.

Mark Andrews marka at isc.org
Fri Jun 3 06:47:41 UTC 2016

In message <CC8CDD00405C5C498FFE95D153A482FE0E05862A at MISOUT7MSGUSRCC.ITServices.sbc.com>, "MURTARI, JOHN" writes:
> Folks,
>                 From some lab testing it appears the answer to the above
> question is NO.... but hope springs eternal!
>                 We'd like to limit RAM usage by BIND (9.9.8/RHEL) on some
> authoritative test servers.  A  load of configured zones would require
> over 10 Gig of RAM, but the boxes only have 4 Gig.   We actually query
> only a few zones for testing (response time is not an issue) and didn't
> want to do the work of changing some standard zone lists and data we use.

Named by default holds authoritative data in memory.  You can use
VM to load very large configurations but it will be slower that

If you use dlz then you can use alternative databases.  Again this
results in a speed penalty.

>                 Hoped we could set max-cache-size to something like
> "1000M" and the server would load zones up to that limit in RAM.  If it
> got a query for another zone, it would bounce an "older" zone out of RAM
> and load the zone needed for the query.  Eventually the cache would
> stabilize.  It appears max-cache-size is just a resolver setting and BIND
> always expects enough memory to load all cofigured zones to RAM.
>                 On a larger test server I even tried setting "datasize
> 1000M" - and that didn't seem to have any effect.  BIND started fine and
> grew to about 10 Gig.  Didn't expect that.

Some mallocs use mmap to work past datasize limits.

>                 Appreciate anyone aware of a config setting that would
> limit usage.
>                 Many thanks!
> John
> ----------------
> John Murtari - jm5903 at att.com<mailto:jm5903 at att.com>
> Ciberspring
> office: 315-944-0998

Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org

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