[TriLUG] RHEL5 mail server dreams

[Paul McLanahan]

I still maintain a Debian email server that I setup for a company for
whom I used to work. I have to say that I'm not sure that running your
own is worth it any more. Unless your main job will be monitoring and
maintaining this email system, or your user base is only a few people
(I'm assuming much larger from what you said), I'd say outsource the
email. Google makes it just too easy and cost effective these days.
Plus you get lots of other cool services at your domain in addition to
POP, IMAP and Web mail.

http://www.google.com/a/help/intl/en/admins/editions.html

That may be a cop out, but I'd just rather spend my time doing things
that relate to my business than managing email backups and worrying
about spammers.

Paul

On Feb 12, 2008 8:56 PM, Kevin Flanagan <flanagannc at gmail.com> wrote:
> Cristóbal,
>
>    Ohh multi part questions!
>
>   There is one question first, how many users?  I know that the volume per
> user is insane, but....
>
>   A few general observations:
>
>    - SPAM, if you are dealing with a lot of mailboxes/users, then you most
> likely need to have a front end process that will make the SPAM vs. HAM
> decision, and handle things.
>
>    - Security, do you want some securemail gateway?  If your user base deals
> with sensitive information then you most likely will need some way that they
> can use a magic word in the subject that trigers a process to send a link to
> the far end, not the actual content, then allowing the desired recipient to
> come get the information in an SSL session.
>
>   - Archive/retention, you need solid policies, specifically what you do is
> not as important as doing what your policies say.  If your written policy
> says destroy everything older than 30 days, then you need to be able to
> prove that you are actually doing it.  Of course this is much more
> applicable to publicly traded companies, but state institutions would likely
> face similar scrutiny.
>
>   - Policies and procedures, you can't just say something,you have to write
> it up, socialize it, get it approved, and publicize it if you have any hope
> of ever being able to enforce it.
>
>   -   Now, for the technical part of things.
>
> 1. Hardware  --- HP servers are what I know, but IBM and maybe even Dell
> have similar feature sets.
>     A "real server"
>   - Redundancy
>      Network connections - Minimum of 2 network connections, uplinked to at
> least 2 different switches.
>      Power - Dual power supplies, connected to different UPS, each connected
> to different circuits.
>   - Performance
>      RAID in hardware
>         Depending on what you are doing for storage, you may not need a lot
> of disks internal, but you need 3 at a minimum, Mirrored disks and a hot
> spare. This may present itself as multiple disks to the OS, but it's just
> for booting anyways.
>   - Out of band management
>      A way to get to the system remotely when it's having issues, KVM over
> IP, Integrated in the server, or an additional box.  In the HP server arena
> you have what's called the Intelligent Lights Out (ILO) network port.  This
> provides for full remote control, BIOS prompts and all.  You can even reload
> a system from a hundred miles away.
>
>    - Storage
>      Being that you are talking about a lot of volume, the performance of
> the spool space is going to be very important.  There are a lot of options,
> SAN, NAS, or local.  Spreading the work across multiple spindles is
> important.  It's very important that you don't have two conflicting types of
> IO loads on the same set of spindles.  SAN folks have a habit of thinking
> that it doesn't matter, it does.
>
>         - SAN - If you are going with SAN storage you need at least 2 Host
> Bus Adapters, preferred 10GB Fibre Chanel.  Typically SAN storage hides the
> spindles completely, you just have LUNs provisioned form the storage folks,
> or perhaps that's yourself.     Get the SAN admins to provision each LUN
> from a different pool of disks, and keep track of what you tell them the
> workload is.  Mail is more likely to be a lot of small files, rather than a
> database that's massive, two very different work loads.
>
>     -  NAS - This could be presented as NFS devices, or ISCSI, although
> ISCSI is often discussed as SAN storage, it's a bit of a gray area.  Same
> rules apply as for SAN in most regards, but you now have network connections
> rather than Fibre Chanel, not so different.  You don't want to have any
> bottlenecks imposed on you by your Storage Admins no matter what the method
> you use to connect to your disks.
>
>    -  Local storage  - If you go this route you will want a large chassis,
> with lots of disk bays and multiple channels to the disk controllers, say a
> chassis that has groups of 4 spindles per channel would allow you to use
> multiple RAID controllers, or at the least channels to get to the disks,
> keep those bottlenecks to a minimum.
>
>
>
>   Honestly the Qmail, Postfix, etc wars don't mean as much to me, that's a
> whole different set of arguements.  Either of those, or most other mail
> handlers will behave in much the same way at the lower levels.  I'm not well
> versed enough to say the details of a Qmail configuration so I won't try to.
>
>
>
> So, perhaps you take my part, and marry that to what someone else has to say
> on the software part, move on to a design that works for you.
>
>
>
>
> Kevin
>
>
>
>
> On Feb 12, 2008 5:03 PM, Cristóbal Palmer <cristobalpalmer at gmail.com> wrote:
>
> > I've been tasked with authoring a proposal for a mail server, but the
> > hardware is currently doing another job and won't be available for
> > several months. Consequently I have a lot of time to dream up what my
> > new mail server *should* be like. Help me dream?
> >
> > You might ask, "What's your volume like?" Dream big. Assume that we're
> > getting more mail than sane people would want to handle and that the
> > hardware will always be woefully inadequate. Unless you're going to
> > buy us a new server, we aren't going to get one. "Don't you have some
> > hardware specs for me to work with?" you ask. I do, but I want you to
> > dream, so I'm not sharing them. Tell me what an ideal mail system
> > would look like if the mail volume is always going to be insane and
> > you have to juggle every kind of mail service known to man.
> >
> > Ideal dreams are fairly complete (ie. touch on everything, not just
> > eg. postfix), have your logic articulated at length, and come out of
> > your own experience, not a whitepaper's. Bonus points for dreams that
> > make the best use of one box + NFS home directories. Any takers?
> >
> > Cheers,
> > --
> > Cristóbal M. Palmer
> > http://tinyurl.com/3apraw "They also abandoned other volumes, later,
> > while fleeing from the librarians."
> > --
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>
>
>
> --
> +---------------------------------------------------+
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> otherwise we leave ourselves vulnerable to those who
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>
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