Re: [vserver] Heartbeat IP Failover

From: Gordan Bobic <gordan_at_bobich.net>
Date: Fri 26 Nov 2010 - 13:40:26 GMT
Message-ID: <4CEFB8CA.8050908@bobich.net>

Adrian Reyer wrote:
> On Fri, Nov 26, 2010 at 10:28:07AM +0000, Gordan Bobic wrote:
>> Indeed, I'm aware of all that. The thing I was enquiring about is
>> the part that integrates with heartbeat. Heartbeat will happily
>> migrate the IPs from one host to the other, but it won't do the
>> naddress --add --nid <guestname> --ip <guestip>
>> part. I was just wondering if there was a pre-cooked resource
>> management script for heartbeat that handles this already.
>
> I am not aware of such a script.
> Having Heartbeat do the IP-Migration is a good way, as it takes care
> about ARP-broadcasting. Don't forget to add 'nodev' to the
> VServer-configuration of that IP.

I see. So if I touch the nodev file in the interface config, the guest
will bind itself to that IP even though it doesn't exist in the host? So
when heartbeat fails the IP over to that host, the guest's IP will start
to work without any further intervention required?

> My Heartbeat-Setups migrate the VServer alongside the IP, so I never need
> to add the IP afterwards. What do the vservers actually do? Just e.g. 10
> IPs that some http-requests get distributet amongst without a special
> meaning of the IP itself? You might save yourself most of the hassle by
> just adding some DNAT iptables-rule to the host, INPUT-chain. It should
> not match packets as long as the IP is not actually present on the
> interface and you state the rule for incoming interface eth0 only.

I can't really do that in my use-case. I need both the primary and
secondary guest to be online at the same time so that the data between
them can be replicating. In case of fail-over, I need the secondary to
be as up to date as possible. That means I cannot fail over the whole
guest. I could use DRBD to make sure the guest FS is mirrored, but
that's a bit overkill for what I need, and a slightly less synchronous
solution provides better performance.

The IPs have different "meanings" and they run different websites and
other services.

It looks like the nodev flag is actually exactly what I want. Thanks for
pointing it out. :)

Gordan
Received on Fri Nov 26 13:41:10 2010

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