memory consumption limit?

Kevin Darcy kcd at daimlerchrysler.com
Sat Sep 10 02:42:50 UTC 2005


How much of that memory is used by the cache, and how much of it is used 
by authoritative data (you said this was the configuration from a 
slave)? There isn't a lot you can do about the memory consumption of 
authoritative data, short of actually deleting records from your zones. 
For cache, though, you can, in addition to max-cache and 
cleaning-interval -- as you've already tweaked -- play with 
max-cache-ttl and max-ncache-ttl, although do so carefully because the 
performance impact of lowering your cache hit ratio can be significant. 
In theory, one can "model" the impact of playing with max-cache-ttl 
and/or max-ncache-ttl somewhat by analyzing cache dumps and querylogs 
(anyone care to write a utility to do this?), prior to actually 
committing anything to production.

Ultimately, if you find that your authoritative data is squeezing the 
amount of memory available for caching, you might want to consider 
separating the caching and authoritative nameservice onto different 
machines. This separation is recommended for security and other reasons 
anyway. Memory usage on an authoritative-only nameserver hardly 
fluctuates at all, compared to a caching nameserver, so you'd just need 
to size the authoritative-only only box(es) according to how much 
authoritative data you have today, plus whatever expansion of hosted 
data you expect in the future.

Another possibility is to recompile BIND with threading disabled. It's 
possible that a non-multi-threading named might have better memory 
characteristics on RedHat.

Then again, you could just buy a memory upgrade for the machine...


                                                                         
                                                - Kevin

P.S. You want a link? Here's a link: 
http://john.redmood.com/osfastest.html. I'm not sure who Jeffrey Rothman 
and John Buckman are, but they seem to prefer Solaris over RedHat for 
running DNS services. As a moderate-to-strong Solaris snob, I tend to 
concur :-)


Pavel Urban wrote:

>Hello,
>
>we're running Bind 9.3.1 on RedHat Linux version 3, ES. After several 
>days we end up with all memory consumed and DNS nearly unresponsive. We 
>have one master and two slaves; this is a part of our configuration from 
>one slave:
>
>options {
>         directory "/var/named";
>         /*
>          * If there is a firewall between you and nameservers you want
>          * to talk to, you might need to uncomment the query-source
>          * directive below.  Previous versions of BIND always asked
>          * questions using port 53, but BIND 8.1 uses an unprivileged
>          * port by default.
>          */
>         #query-source address * port 53;
>         allow-transfer { 194.228.2.61/32; 193.85.7.100/32; 
>193.85.1.12/32; 194.228.1.194/32; 194.228.2/24; };
>         allow-recursion { 127.0.0.1; 194.228/16; 192.168/16; 172.16/12; 
>10/8; 80.188/16; 83.208/16; 85.70/15; };
>         notify yes;
>         recursion yes;
>         max-transfer-time-in 8;
>         transfer-format one-answer;
>         transfers-in 80;
>         transfers-out 80;
>         transfers-per-ns 40;
>         coresize default;
>         max-cache-size 200M;
>         files 1024;
>         stacksize default;
>         cleaning-interval 30;
>         interface-interval 0;
>         recursive-clients 50000;
>};
>
>
>This is 'top' output from the same machine:
>
>46 processes: 44 sleeping, 2 running, 0 zombie, 0 stopped
>CPU states:  cpu    user    nice  system    irq  softirq  iowait    idle
>            total   58.2%    0.0%    1.9%   0.5%     1.5%    5.9%   31.5%
>Mem:   511736k av,  505212k used,    6524k free,       0k shrd,    2988k 
>buff
>                     385208k actv,   72524k in_d,    9404k in_c
>Swap: 1052248k av,  486172k used,  566076k free                    8668k 
>cached
>
>   PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME CPU COMMAND
>22312 named     25   0  473M 435M  1136 R    59.6 87.2  3610m   0 named
>22314 named     15   0  473M 435M  1136 S     0.3 87.2 209:11   0 named
>
>
>Can you give me a tip what to tweak, or a link to the proper article/web 
>page? Thanks!
>
>  
>




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