Load Balancing + File Locking

[Boulytchev, Vasiliy]

Thoughts and setup  (mx is out of the questions, sorry, network is different
here)

A = Mail Server (CommunigatePro)
S1 = Mailscanner node 1
S2 = Mailscanner node 2
S3 = Mailscanner node 3

On A, we have all of our domains (hundreds).  I will not go into detail of
how much redundancy this thing has, and why we cant simply point to the
scanners with mx records, but here is my idea.  On A, have 2 NFS-shared
folders (certainly on a private network and gig nics).  One Incoming, which
is handled by cgp2ms and the other is Submitted, handled by ms2cgp.  Now,
say these three nodes keep grabbing batches of mail from these mount points,
process them, and spit things out in the final Submitted location for Cgate
to push the mail out.  Mailscanner should not have any issues with handling
the mounted directories, the only thing I am worried about is file locking
and fragmentation.
        So the question is, how do I prevent (or is it a big deal), that
lets say... There are 300 messages in the Incoming directory at any moment.
Mailscanners pick that queue up, crunch on it on each node, and spit it out
in the Submitted directory.  Now we start to ask these questions:
        1.)     Am I tripple scanning each message and not getting any
performance back.
        2.)     As of right not, I think there are 2 ways MS goes through
the Incoming directory, sequentially and non-sequentially (if there are more
than x amount of messages).  How do I tell MS to share the load!
        3.)     Maybe modify cgp2ms to spit things out into different
Incoming directories, therefore walking right around the file locking
problem.

IDEAS?   Who else is doing this?


Vasiliy Boulytchev
Colorado Information Technologies, Inc.
http://www.coinfotech.com

-----Original Message-----
From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On Behalf
Of Martin Hepworth
Sent: Friday, October 01, 2004 10:59 AM
To: MAILSCANNER at JISCMAIL.AC.UK
Subject: Re: Load Balancing + File Locking


Vasiliv

that's what's achieved by round-robin DNS.

Or do you a central file store for all queues, quarantine dir etc. You could
always have a third machine with the file stores on it that's mounted by all
the other hosts, but you still have the issus of the fileserver going
down...

--
Martin Hepworth
Snr Systems Administrator
Solid State Logic
Tel: +44 (0)1865 842300


Boulytchev, Vasiliy wrote:
> :))))))))))))))   Brilliant! :)))))))))))))))))
>
> This is definitely a nice way to use round robin DNS... To your advantage
> even.  Sweet.
>
> Unfortunately this don't help us :(.   We must load balance this sucker.
If
> we will not have loadbalancing, we shall achieve the same with running
> sendmail on each mailscanner box, and vuala..... But I really want a
> Mailscanner Cluster!  I want redundancy!
>
>
> Vasiliy Boulytchev
> Colorado Information Technologies, Inc.
> http://www.coinfotech.com
>
> -----Original Message-----
> From: MailScanner mailing list [mailto:MAILSCANNER at JISCMAIL.AC.UK] On
Behalf
> Of Denis Beauchemin
> Sent: Thursday, September 30, 2004 2:56 PM
> To: MAILSCANNER at JISCMAIL.AC.UK
> Subject: Re: Load Balancing + File Locking
>
>
> Boulytchev, Vasiliy wrote:
>
>
>>Ladies and Gents,
>>       The loads on the mail server require us to start moving
>>Mailscanner with Spam and Virus filtering to other machines.  Questions:
>>       1.)     How does MS do the locking on files in the submitted
>>directory (after cgp2ms)?  If NFS3 is used to mount that shared folder
>>on say 3 servers designated to only scanning mail, how do we avoid
run-ons?
>>       2.)     Idea: if the local procs keep track of locking, then we can
>>toss all that into mysql for example? :)))  Just thinking of ways to
>>add scalability.
>>
>>
>>
>
>
> Vasiliy,
>
> We have 2 MS servers for incoming mail and they don't share any spool
> directory.  They are separate servers and the load balancing is done
through
> the MX records.  Our 2 servers were not identical (one was about twice as
> fast as the other) and we had the following:
> # host -t mx usherbrooke.ca
> usherbrooke.ca mail is handled by 10 smtpe1.usherbrooke.ca.
> usherbrooke.ca mail is handled by 10 smtpe2.usherbrooke.ca.
> usherbrooke.ca mail is handled by 10 smtpe3.usherbrooke.ca.
>
> Here smtpe1 and smtpe3 are the same machine (the fastest one) with
different
> IP.  It received close to 2/3 of all mail.
>
> I just replaced the slowest one (smtpe2) by a machine identical to the
> fastest one (smtpe1) so I asked our DNS guys to drop the smtpe3 name.
>
> Denis
>

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