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I have UCARP working but the documentation is confusing and I've found at least 3 different ways suggested in blogs (these are old and don't all seem to work). I currently have ucarp- lines added to /etc/network/interfaces under ubuntu but now I need to set it up on CentOS with multiple VIPs per interface.

In Multiple UCARP VIPs on single Interface with Debian/Ubuntu Evan Anderson says that this should be easy in CentOS. I've installed the UCARP package but there are no init scripts and it ignores my .conf files so I am wondering if this is the right way to go about it.

Can anyone describe the right way to set this up or link to a recent example that works?

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Is there a reason you're not using Heartbeat instead? – Joel K Jan 30 '11 at 16:59
because it seems heartbeat has grown into something which is completely over the top for my needs. I don't need a cluster I just need a simple VIP. Also it's behavior on splits is unclear. Someone has said that in that case neither node will respond. – JamesRyan Jan 31 '11 at 11:44
(everywhere says not to use the simpler v2 because it is buggy and unreliable) – JamesRyan Jan 31 '11 at 11:55
What version of CentOS? The EPEL repository package seems completely sane for 5.x – Kimvais Feb 1 '11 at 9:04
Yep it seems that the EPEL one is pretty much the same as the accepted answer just in a different folder. Somehow I was pulling it from some weird repo which just confused the situation further. In hindsight it is obvious really, thanks. – JamesRyan Feb 2 '11 at 21:41
up vote 4 down vote accepted

I'm using the ucarp-1.5.2-1.el5.rf package (from the DAG repository) on CentOS 5.5. It creates a /etc/sysconfig/carp directory into which you'd place vip-xxx.conf (where xxx is an arbitrary integer from 1 to 255, as mandated by the /etc/init.d/carp script) files, each containing the configuration details for that discrete ucarp instance. You'll also need to create /etc/sysconfig/network-scripts/ifcfg-ethX:Y configuration files containing the IP address details for each virtual IP instance.

There's an example configuration file in the package that can assist you in getting all of this put together.

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Kinda off-topic but I can mention VRRP which I recently became aware of. I think I'll give it a try to use instead of UCARP.

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yup I did also look at keepalived – JamesRyan Jan 31 '11 at 19:57

Looks like you need a start script - some examples are here:

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this is pretty much what I have done, just doesn't seem very neat :) – JamesRyan Jan 31 '11 at 19:58
The EPEL package comes with a startup script – Kimvais Feb 1 '11 at 10:37

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