*** MULIG SPAM*** Re: Distributed setup with realtime failover/balancing

[Julian Field]

jonas at vrt.dk wrote:
> Hello
>
>   
>>>> Hmm well it might be overkill, but definitely not for the above
>>>> reason. Your
>>>> describing the normal basic smtp loadbalancing/failover that mx records
>>>> provides, which is fine. The problem is in a mailscanner/mailwatch
>>>>         
>> setup
>>     
>>>> there are more components than simply the smtp incbound traffic. After
>>>>         
>> a
>>     
>>>> remote server have send a mail to either of the mx records, the mail is
>>>> stored temporary on one of the boxes, if that box goes down, that mail
>>>> and
>>>> any mail quarantined on the box is unavailable to users. Which is not
>>>> acceptable.
>>>>         
>> How is an LVS solution going to solve that?  However you implement it
>> the connection will be load balanced across the MailScanner boxes and
>> they will spool to disk.  Once the connection is closed the LVS is no
>> longer involved.
>>
>> If this is a requirement then you will have to move to something that
>> analyses the email as it is being spooled to disk (e.g. a milter). Also
>> how are you going to track whether a message has been delivered or not?
>>
>>     
> I am sorry, I have not been very clear. The main reason for me to desire a
> distributed setup, is to have the quarantine directory always be available.
> That's where DRBD comes in. ultramonkey/lvs/heartbeat is just to spread out
> the load on apache and mysql. And also to facilitate failover.
>
> Mails that are in actual transit (meaning in the in or outgoing queues) are
> more acceptable to loose, than users not being able to release mails from
> the quarantine. At least they are for me.
>
> I hope that explains it a little bit better.
>
> Best regards
>
> Jonas Larsen
>
>   
Do remember that multiple MX records with the same priority number will 
provide you with load-balancing between multiple MX hosts for free. You 
need to have a third system running MailWatch (I think) but the mail 
load balancing doesn't require any special hardware or software at all.

Do it the cheap way :-)

Jules

-- 
Julian Field MEng CITP
www.MailScanner.info
Buy the MailScanner book at www.MailScanner.info/store

MailScanner customisation, or any advanced system administration help?
Contact me at Jules at Jules.FM

PGP footprint: EE81 D763 3DB0 0BFD E1DC 7222 11F6 5947 1415 B654
For all your IT requirements visit www.transtec.co.uk



-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
For all your IT requirements visit www.transtec.co.uk