Re: [exim] Patch: ClamAV server failover

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Author: Adam Stephens
Date:  
To: Warren Baker, exim-users
Subject: Re: [exim] Patch: ClamAV server failover
Warren Baker wrote:
> Hi Adam,
>
> This is great! However would it not make sense to randomize the server
> you connect to? From the below it appears if the 1st server defined is
> in the list and always available then it will always use that server
> instead of 'load balancing' the connections. Just expanding this a bit
> further there was a patch last year sometime (which hasn't been added
> to the source tree) to have multiple SpamAssassin servers utilizing an
> MX style approach. Maybe its an idea to utilize that?
>
> Have a look at
> http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20060821/msg00050.html
>
>
> I know the answer is "patches accepted" but my C is not that great :)
>
> Thanks,
> Warren
>


The DNS queries are against a BIND server; this returns the resource
records in a randomised order (see the rrset-order documentation), so
all the servers are used.

That said, although all the servers are used the distribution of queries
is very uneven, and I'm not sure why. This doesn't actually bother me
much; the servers are running spamassassin as well, and the clamAV load
is trivial by comparison, so I haven't given it much thought.

Adam.

--
--------------------------------
Adam Stephens
Network Specialist - Email & DNS
adam.stephens@???


>
> On 18 Jul 2007, at 6:01 PM, Adam Stephens wrote:
>
>>
>> We've had some problems with our ClamAV servers recently. Exim will
>> only try one of them, so when one of the servers is unavailable the
>> messages it would have scanned are deferred (or not scanned, if you
>> have /defer_ok set).
>>
>> The attached patch makes Exim try multiple clamAV servers; it still
>> only accepts one hostname in the configuration file, but with this
>> patch Exim will try each of the IP addresses associated with that
>> name until it finds one that works, or it's tried them all.
>>
>> We've been using this in production for about a month, with no
>> problems. As usual, however, if you do use it you do so at your own
>> risk!
>>
>> Adam.
>> --
>> --------------------------------
>> Adam Stephens
>> Network Specialist - Email & DNS
>> adam.stephens@???
>>
>