Dual server Varnish setup

[Ben Dodd]

Something like this:

director cr-backends round-robin {
  .retries = 5;

  {
    .backend...
  }

  # Repeat the above entry for each web server.
}

director cr-varnish round-robin {
  .retries = 4;

  {
    .backend...
  }

  # Repeat the above entry for each varnish server.
}

sub vcl_recv {

  set req.backend = cr-varnish;

  if (req.http.X-Via-Varnish || req.restarts > 3) {
    # Request is coming from the other server.
    # Ignore busy objects to avoid race condition.
    set req.hash_ignore_busy = 1;
    set req.backend = cr-backends;
  } else {
    set req.http.X-Via-Varnish = "true";
  }
}

Thanks, Ben

On 10 Feb 2011, at 14:14, Martin Boer wrote:

> I would also add weights so that each varnish prefers to ask its sibling
> say 250 times more often than asking the app-server.
> This will ensure that both varnishes will be as filled and as equal as
> possible.
> I don't know if 250 could be replaced by a larger number but this works
> for me.
>
> Regards,
> Martin
>
> On 02/10/2011 02:46 PM, Laurence Rowe wrote:
>> On 8 February 2011 23:05, Ben Dodd<B.Dodd at comicrelief.com>  wrote:
>>> Given this functionality, does anyone know what the VCL is required to implement this dual server Varnish setup scenario?
>>> http://varnish-cache.org/trac/wiki/VCLExampleHashIgnoreBusy
>> Something like this should work:
>>
>>
>> backend appserver { ... }
>> backend other_varnish { ... }
>>
>> # Server 1
>> sub vcl_recv {
>>     set req.backend = other_varnish;
>>     if (req.http.X-Via-Varnish || !req.backend.healthy) {
>>         # Request is coming from the other server.
>>         # Ignore busy objects to avoid race condition.
>>         set req.hash_ignore_busy = 1;
>>         set req.backend = appserver;
>>     } else {
>>         set req.http.X-Via-Varnish = "true";
>>     }
>> }
>>
>> # Server 2
>> sub vcl_recv {
>>     set req.backend = other_varnish;
>>     if (req.http.X-Via-Varnish || !req.backend.healthy) {
>>         # Request is coming from the other server.
>>         set req.backend = appserver;
>>     } else {
>>         set req.http.X-Via-Varnish = "true";
>>     }
>> }
>>
>> Laurence
>>
>> _______________________________________________
>> varnish-misc mailing list
>> varnish-misc at varnish-cache.org
>> http://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
>>
>>
>
>
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