Re: Sharing DNS cache among Squid workers

On 01/13/2011 03:20 PM, Robert Collins wrote:
> On Fri, Jan 14, 2011 at 11:13 AM, Alex Rousskov
> <rousskov_at_measurement-factory.com> wrote:
>> On 01/13/2011 02:18 PM, Robert Collins wrote:
>>> Have you considered just having a caching-only local DNS server
>>> colocated on the same machine?
>>
>> I am sure that would be an appropriate solution in some environments. On
>> the other hand, sometimes the box has no capacity for another server.
>> Sometimes the traffic from 8-16 Squids can be too much for a single DNS
>> server to handle. And sometimes administration/policy issues would
>> prevent using external caching DNS servers on the Squid box.
>
> This surprises me - surely the CPU load for a dedicated caching DNS
> server is equivalent to the CPU load for squid maintaining a DNS cache
> itself; and DNS servers are also multithreaded?

A general-purpose caching DNS server usually does more than Squid does,
so I would not be surprised if it uses more CPU cycles. And even if a
super-optimized DNS server is fast enough, administration/policy issues
may still prevent it from being installed on Squid boxes.

And FWIW, BIND multi-threading is rather poor. I am sure there are
faster servers out there, but the "most popular" one may not work as
fast as the DNS server component of SMP Squid.

Thank you,

Alex.
Received on Wed Jan 26 2011 - 01:04:20 MST