[Unbound-users] Configuration suggestions?

Daisuke HIGASHI daisuke.higashi at gmail.com
Sat Apr 13 06:21:39 UTC 2013

Hi Anders,

Generally larger cache memory can improve latency (cache hit ratio)
because it can keep more records in cache. I'm not certain whether too
much memory introduce something harmful or not (except power
consumption or failure rate of memory modules).

But according to my test, around 3-4GBs memory per one Unbound cache
server seems to be enough (e.g. rrset-cache-size: 2g, msg-cache-size:
1g) even if in large ISP environment. More memory won't improve cache
hit ratio meaningfully. PowerDNS recursor doc gives similar suggestion

Note that Unbound will consume more memory than you specified due to
malloc() overhead [2] and we will need more cache memory as
DNSSEC-signed zone is deployed more widely.

[1] http://doc.powerdns.com/html/recursor-performance.html
   "Cache hit rate does not improve meaningfully beyond 4 million
max-cache-entries per thread…. "
[2] http://www.unbound.net/documentation/howto_optimise.html

 Daisuke HIGASHI <daisuke.higashi at gmail.com>

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