[Linux-cluster] sharing same ip with 2 services on two nodes

[Gordan Bobic]

You can't have the same IP on multiple machines at the same time. That
much should be obvious before even thinking about clustering.

You can, however configure floating IPs as resources that RHCS will
fail over between cluster nodes. Only one node will have a particular
IP address at any one time, but if that node fails, the floating IP
will get migrated to one of the surviving nodes.

Any number of services can run on a floating IP. There is no need
to have one floating IP per service.

Gordan

On Fri, 17 Apr 2009 13:23:30 +0200, ESGLinux <esggrupos at gmail.com> wrote:
> Hi,
> 
> thanks for your answer
> 
> I suspected  so,
> 
> can I say as an axiom: One service needs One IP? ( One man, One vote ;-)
)
> 
> and if is this true, has it sense to configure ip resources as shared? it
> must be better to configure as a private resource, isnt it?
> 
> Greetings,
> 
> ESG
> 
> 2009/4/17 Juan Ramon Martin Blanco <robejrm at gmail.com>
> 
>>
>>
>> On Fri, Apr 17, 2009 at 12:57 PM, ESGLinux <esggrupos at gmail.com> wrote:
>>
>>> Hello all,
>>>
>>> I have a doubt about using the same service ip with two diferent
>>> services
>>> in two diferent nodes of my two-nodes-cluster.
>>
>>
>>>
>>> I´ll explain it a litle:
>>>
>>> I have two services: BBDD and HTTPD
>>>
>>> I have configured a shared IP: 192.168.1.100
>>>
>> Hi,
>> You _must_ use a different  IP, cannot have the same IP on different
>> machines.
>>
>> Greetings,
>> Juanra
>>
>>>
>>> two nodes: node1 and node2.
>>>
>>> When I run the two services on node1 all runs ok. If I try to relocate
>>> one
>>> service, with
>>>
>>> clusvcadm -r BBDD -m node2
>>>
>>> it fails with the error:
>>>  in.rdiscd[4805]: setsockopt (IP_ADD_MEMBERSHIP): Address already in
use
>>>  in.rdiscd[4805]: Failed joining addresses
>>>
>>> I suposse that is because one services is on node1 with the ip and the
>>> other trys to run in node2 with the same ip.
>>>
>>> So my question is if it is possible to run the services this way or I
>>> need
>>> an ip per service?
>>> (I have tested that with 2 diferent ips I can run BBDD on node1 an
HTTPD
>>> on node2)
>>>
>>> Thanks in advance
>>>
>>> ESG
>>>
>>>
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>>>
>>
>>
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