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Home » Kerio User Forums » Kerio Connect » Kerioconnect failover; syncing mailstores/setting (Regarding some help setting up a failover situation)
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HugoZonderland

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Introduction
I would like to create a failover situation with 2 Kerio Connect hosts.

Currently I use Kerio as an alternative mailserver/imap from what I got from my webhoster. Because I have several devices which I wanna use to keep synchronized agenda's, contacts and email. Since i'm stuck to limited storage on my webhost.

How its configured
Both servers are located at different locations and both are connected to ADSL internet connections (location A 50/5mbit and location B 8/1mbit).

Location A is seen as (new) main/primary server. The server is running Windows Server 2008 x64 within an ESXi environment. The server is behind a router (ports are forwarded) and pfSense virtual machine.

The server located at location B is running Windows Server 2008 x64 (will be reinstalled and have some hardware replaced in the future). The server is behind a single router with ports forwarded.

Lets say that I have locationa.domain.com and locationb.domain.com. And the email is pulled from my webhost wich is mail.domain.com. How do I set this up in my DNS management?

But what happens next? How do I make sure that I have both mail stores and settings synced between both locations?

[Updated on: Thu, 06 September 2012 12:52]

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HugoZonderland

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Is anyone familiar with this tool? Could be used to synchronize host A and host B.

Look for DSYNCHRONIZE on this website: http://dimio.altervista.org/eng/

[Updated on: Mon, 24 September 2012 12:43]

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HugoZonderland

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Incredible having 10643 views on my topic but really zero response.
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pcunix

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Did you look at http://www.kerio.eu/eu/connect/third-party ?


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Marathon Technologies Seamless failover and failback on Windows servers.


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Tony Lawrence
Kerio Preferred Partner and Reseller
Certified for Connect, Control
http://aplawrence.com
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HugoZonderland

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I did. I'm sorry that I forgot to mention that this is just a home-enviroment. No enterprise or business solution that I'm looking for.
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pcunix

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The heart wants what the heart wants, but I really don't see the point of this in a home environment.

See my http://aplawrence.com/Kerio/failover.html and then let's continue the discussion here.

Tony Lawrence
Kerio Preferred Partner and Reseller
Certified for Connect, Control
http://aplawrence.com
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HugoZonderland

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Well Tony,

About the discussion; you say it doesn't really mind being offline for a couple of hours/days. For home or small office use indeed I can agree on that. But that doesn't take away that its simply handy to have something like this at hands.

Since I'm a student its always good to pickup a scenario like this and try to get this working no matter what. So the main reasons are learning curve and I get some joy creating a situation like this.

The ISP where I got the SMTP server offers an API. It allows me to write scripts that could be used to update DNS records for instance. I could program a script that could check the status on HOST A, when offline update the DNS so that HOST B becomes the main server. When HOST A gets back online again all I need is the mailstore to be synced again and be "up and running" again.


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pcunix

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OK, so this is a learning exercise rather than real need.

Yes, you could switch DNS MX as you propose. I'd suggest Linux boxes and rsync to keep it up to date.

Your scripts need to be VERY aware of which server is active currently or you will really make a mess. You also have to be sure you keep the same versions on both machines and you can't easily do that without two licenses.

SSL certs also.. what else.. let me think Smile

Tony Lawrence
Kerio Preferred Partner and Reseller
Certified for Connect, Control
http://aplawrence.com
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HugoZonderland

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Let me rectify this:

- My e-mail gets delivered at my ISP. (mail.domain.com) got several.
- My Kerio Connect machine downloads the e-mail and delivers it to the right mailbox.
- Kerio Connect is using SMTP rely to deliver the e-mail to the SMTP server online.

So I wont be needing MX records. All I'll need to update is that the DNS directing to the mailserver:
kerioconnect.domain.com from IP 1.1.1.1 to 1.1.1.2 for example.

As the script is able to update the DNS record it is able to verify the current used ip address to match the ip address of a pre-definend "primary" server.

The location B server was what the server at location A is now. All I did was using kmsrecover to move from locations. So I'm geussing all the settings as for the SSL certificates are located somewhere in the mail store. Thus using some sync software (DSYNCHRONIZE) should make it possible to create a live copy of my primary mail server on a second location.

I'm going to test this soon on my ESXi machine using 2 Windows Server 2008 R2 machines and this DSYNCHRONIZE tool. However I did read somewhere that Kerio locks files when opening/editing/writing. This could cause problems with the sync tool, right?
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pcunix

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If Kerio is not using advisory locks. Do we know if they are and if it is different on different OSes?


Tony Lawrence
Kerio Preferred Partner and Reseller
Certified for Connect, Control
http://aplawrence.com
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HugoZonderland

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Sorry what do you mean by that?
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pcunix

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There are different kinds of file locking. Mandatory locks and advisory locks.

Mandatory locks are enforced by the operating system. Advisory should really be called "cooperative" - programs agree to respect the locks but any program that has no knowledge of them won't be affected at all.

See my http://aplawrence.com/Basics/locking_methods.html for a gentle intro..

I don't know what Kerio uses.. and it could be different on Linux and Windows.

Tony Lawrence
Kerio Preferred Partner and Reseller
Certified for Connect, Control
http://aplawrence.com
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HugoZonderland

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I still have to setup the test environment, if syncing causes problems I'll reply here.

Since i'll be using Windows Server 2008 R2 machines there would be no difference on OS level.
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pcunix

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Well, I have this nagging thing in the back of my mind about certain Windows sync tools not doing something right.. my stupid brain isn't bringing it up for me and I'm not finding it in any of my tech notes either but SOMETHING is bugging me about Windows syncing..

As my brain won't cooperate, consider using "rsync" rather than the typical Windows "ditto" or whatever the sync du jour is now.. yes, the learning curve is higher but it works and I KNOW some of the "easy" things have bugs.


Tony Lawrence
Kerio Preferred Partner and Reseller
Certified for Connect, Control
http://aplawrence.com
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HugoZonderland

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I'll look into rsync as well.
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