Timeouts during cache cleaning and zone collection

Nod none at nospam.none
Tue Jun 21 20:28:39 UTC 2005

On Tue, 21 Jun 2005 14:23:14 -0400, "Joshua Coombs" <jcoombs at gwi.net> wrote:

>> I'm having a similar issue to this, namely the cache cleaning.
>> It seems that whenever the cache-cleaner runs, it blocks requests to 
>> the
>> nameserver. While the secondary cache will take over, most of the 
>> clients will
>> see a 5-6 second delay (Windows) before using the secondary server. 
>> Setting the
>> cache cleaner to run once a minute takes about 7-8 seconds to clean. 
>> Leaving it
>> at an hour means it will be cleaning for about 20 minutes.
>> Turning off the cleaner results in bind using up all the ram and 
>> getting killed
>> by the OS.
>> The server in question serves about 11000 zones. Dual xeon 2.8, 4gb 
>> ram, FreeBSD
>> 5.4 64 bit, MAXDSIZ, MAXSSIZ, and DFLDSIZ set to 2gb at the moment. 
>> Generally,
>> about 800-900 recursive clients at any given time.
>> If anyone has any ideas how to improve the cache cleaner 
>> performance, it would
>> be most appreciated. As it is now, the nameserver 'going away' 
>> happens far too
>> often, and is very noticable.
>This issue has bit us pretty hard as it causes freeradius to fail auth 
>attempts during bind's cleaning windows.  This occurs weather or not 
>the freeradius box has multiple resolvers defined.  Our solution, 
>we're moving away from bind wherever we can till a fix is tested. 
>We've had excellent luck with pdnsd, the latest dev builds are working 
>quite well.
>Joshua Coombs 

I've found somewhat of a workaround, but it involves setting the max-cache-size
to about 16 megabytes. The CPU is constantly thrashing with a 1 minute cache
cleaning, but it doesn't go down for an perceptible time period. Generally the
clenaning takes less than 0.8 seconds, not enough to be complained about.

Not an ideal solution, but an immediate one.

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