Redundant and Geobalancing setup

[Cedric Malitte]

Hi Daniel,

I do already have a backup server where I replicate the mails every 4 hours
using imapsync.
Not the best, but this is workable.
The one time I redirected to backup server, people where complaining that
they were having duplicate mails ( this was pop access )
I also have mx backup with easydns, was part of the plan so I use it.

We have three main offices, a few on the road managers and many dealers.
Dealers run their own business under our trademark, and use the same
domains for mails as ours (head offices).
I mean every mailbox is on the same server.
May be not the best.

I have the mandate to get everything running smooth.
There can be outages, but not too long.
One hour is too long for some....

It will also be to educated people here and there.
I understand that what they want costs money, but I'm not able to make them
understand that what they want is not plug and play cheap solution.

But, I'm going to test on VMs dovecot on glusterfs with dovecot director if
I manage to get it working properly.
Might be a challenge, but who knows, it might work :)

Best regards,

Cedric

2016-02-15 4:16 GMT-05:00 Daniel Tröder <troeder at univention.de>:

> On 02/13/2016 04:00 AM, Cedric Malitte wrote:
> > Hi,
> >
> > I use dovecot for a long time now, but only as a single isolated server
> > each time.
> >
> > I joined a company a few years back. We had trouble with compagnies
> hosting
> > our mail, supposedly full redundant and so on.
> >
> > The company is small, but we have many dealers around the world, and it's
> > growing.
> >
> > Mail became the fist choice for clients to contact the dealers.
> > No mail, and we loose sales.
> >
> > For now we have a single server ( with a backup ) on east coast.
> > And sometimes peoples from EU complain about speed.... ah users :)
> >
> > What I'd like to implement is a redundant system with 2 servers, one in
> NA,
> > one in EU.
> > And I'd also like to be able to add another server if needed on the west
> > coast.
> >
> > Idea is, that if a server goes down, the users will be able to still
> > receive and send mails, and never loose mails.
> >
> > For geobalacing and failover, I read that I can do it with DNS ( I'm with
> > easydns ).
> >
> > I'm at the first stage where I collect informations that I try to
> > understand and foresee a solution.
> >
> > First idea is to set up servers with a mysql master, slaves and a
> glusterfs
> > in replica mode on the servers.
> > I tried glusterfs on FreeBSD and OMG, it's slow as hell ! ( well maybe
> it's
> > a trouble on the VMs nics )
> > On centos it's way better.
> > But I read there might be trouble/index corruption for the mail storage
> on
> > "shared" space using maildir.
> >
> > I also had a look at dsync, but I wonder if it can be used on more than 2
> > servers.
> >
> > I found many pages on dovecot clusters using shared storage NFS mounted,
> > but I feel it's not really what I need as the servers will be in
> different
> > datacenters.
> >
> > So any guide, clue hint would be really appreciated for me to do my
> > homework !
> >
> > Regards.
> >
> > Cedric
>
> Hi Cedric,
>
> I think a simpler solution will not just be cheaper but less complex -
> and with that more reliable:
>
> The speed problem of the EU users is probably just feeling. You should
> quantify it for both SMTP and IMAP. Collect that data for the scenarios
> that your users complain about (is it to a partner or inter-office?).
> Only then can you work on a solution that you will be able to prove to
> them, is better. This is paramount.
>
> My suggestions:
> * Server on the east cost is good for both NA and EU.
> * Good (better?) internet connection for the EU office, prioritize SMTP
> vs HTTP in router/firewall (fast internet is WAY cheaper than cluster
> setups plus administrators)
> * SMTP relay in EU _office_, so that _sending_ mails is with LAN speed
> for users
>
> Create a redundant setup for SMTP and IMAP together on the east cost.
> You'll get redundancy without the WAN problem.
>
> Setup a secondary MX in a different data center for uber-redundency. It
> will not enable your users to read their mail in case the 1st data
> center is on fire, but no client mails will get lost, as they will be
> queued on the 2nd MX - better read client mails late then never!
>
> Setup a clone of the primary server at the 2nd MX and sync mails &
> backup there on a hourly basis. If the 1st data center is not back in an
> hour, you can still switch DNS to the 2nd site and your users will have
> had a very short downtime.
>
> The result is not a top-notch 100% solution, but it is simple and
> everything is implemented on application layer. That gives you freedom
> to switch products, hardware, platform and administrators(!).
>
> Ask your customer/supervisor what uptime is necessary and how much they
> are willing to pay. The SLAs of MS/Google/etc offer up to 99.9% (~9
> hours downtime per year). If that is the goal, then they should pay the
> price for their equipment and staff. For anything less my argument is
> less complexity for higher reliability.
>
> Greetings
> Daniel
>
>