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PyromanciFlag for United States of America

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Lan Failover

OK, I currently have 2 Rack mount machine nearly identical sitting in a local datacenter. The are nothing more then MySQL database servers. their raid setup is Raid 0 (4 drives) but i am using drbd to do a network based Raid 1 (bidirectional) with MySQL partition.

I also have configured on the 2 machines a heart beat service monitor for a failover system if machine 1's MySQL goes down.

Now this method seems fine, but i have noticed some cases this fail over method is not good enough. So I want to add one more failover into my setup. I want to get a router that suppose a LAN based failover.

But i can not find a cost effective solution atm. I know the Cisco Pix 515 support this, but its way more then what i need.

Any one have any suggestions for a good cost effective gigabit router that supports this?
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Steve Jennings

Check out Adtran . . . they do VRRP and they are fairly inexpensive. And the tech support is without doubt the best in the industry. You can call the Adtran 800 number and ask for presales support.

I am not an Adtran employee.

Good luck,
Steve
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Anyone else have any other suggestions? I mean, i am using 2 machines and only 2 machines. Have of the products i know that can handle failover as way to much to them for my needs. I know there has to something out there for a smaller network setup.
Possibly, a in depth explaination of what i am really looking for might help.

Here is what I was thinking.
I have a Service IP. Lets say 192.168.0.1 and that's the IP all the traffic bound for the MySQL database points too.
Then Machine 1 IP would have a IP of lets say 192.168.0.2
Then Machine 2 IP would have a IP of lets say 192.168.0.3

normally all the traffic going to 192.168.0.1 would be forwarded to 192.168.0.2.

Lets say the Nic card in Machine 1 died, my current heartbeat and proccess based failover system can't catch that.  So i want a router/switch to auto detect that 192.168.0.2 is offline and send it 192.168.0.3 instead.
Basically, you are describing a load balancer. The device that would send traffic to either the .2 or .3 device would have the service address of .1. And the .1 device would send heart beat queries to the 2 MySQL instances and direct traffic to the one that was a) marked active or b) responded first or c) the one that it determined was up and available.

Without a load balancer, how would the "traffic director" know that either instance A or instance B had failed? In other words, it sounds like you have a heartbeat between Machine 1 and Machine 2 so that if the instance on Machine 1 dies, the instance on Machine 2 becomes the active instance. Is that right? If that's the case, the router or device directing traffic would have to know which Machine to send traffic to . . . and if the inbound traffic was being sent to a service address the "router" would have to be able to change the actual address to the .2 or .3 address.

In your example, you mention a service address . . . as far as I know ONLY a load balancer has the "smarts" to present a virtual IP address (a service IP in your terminology) and then redirect traffic inbound to the service address to an actual address of .2 or .3.

F5 and Citrix and Radware and a couple of others sell devices that do basic load balancing and fail over.

Good luck,
Steve
Um . . . I forgot you said "cheap"

F5 and Citrix and Radware are NOT cheap.

Maybe you can download the free version of the java servlet based load balancer and make it work for you. You'd need to be somewhat proficient in java so you could do basic servlet mods to accommodate your inbound traffic type . . .

There aren't too many open source load balancers that work worth a crap. Most load balancers are needed where there's some sort of connection persistency required. But in your instance, it sounds as though you don't really need the "load balancing" function, just the failover protection that a typical load balancer provides.

Good luck,
Steve
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Pyromanci
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