max-cache-size rule of thumb?

[David Forrest]

On Mon, 18 Apr 2011, Dennis Perisa wrote:

> Hi all,
>
> Is there a rule of thumb when setting max-cache-size?  e.g. max physical
> memory * 0.4
>
> Is there even a need to set max-cache-size on a server with plenty of memory
> (>10GB) running only BIND?
>
> Regards
> Dennis
>

Dennis, since getting the answers from cache is usually faster (and 
therefore more efficient) than recursing, I think the question is really 
what is the definition of "plenty of memory".  If bind's performance is 
hindered because of available memory then a limit on the cache size may be 
warranted, as also an increase of memory may be.  In the example, a 
max-cache-size of .4*10GB leaves a residual pool that far exceeds BIND's 
requirements.  The answer must be determined empirically;  If performance 
is adversely affected then (and only then) limit the cache size .

Dave

-- 
David Forrest 
Maple Park Development Corporation
St. Louis, Missouri