mysql-mmm

what mechanism does mmm use to configure the IP addresses? how do I troubleshoot why it is not happening?

Asked by ntucker

I can't find a description of how the roles' IP addresses get automatically configured. I can switch roles among my hosts, but no configuration of the network interfaces occurs, and I'm not sure how to troubleshoot it. There don't seem to be any messages in the log about it.

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Pascal Hofmann
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Walter Heck (walterheck) said : 		#1

It happens through ARP requests. Execute an 'ip addr show' on the
machines to see the IP- addresses they have assigned.

Cheers,

Walter

On Sat, Mar 27, 2010 at 06:25, ntucker
<email address hidden> wrote:
> New question #105641 on mysql-mmm:
> https://answers.launchpad.net/mysql-mmm/+question/105641
>
> I can't find a description of how the roles' IP addresses get automatically configured.  I can switch roles among my hosts, but no configuration of the network interfaces occurs, and I'm not sure how to troubleshoot it.  There don't seem to be any messages in the log about it.
>
>
> --
> You received this question notification because you are an answer
> contact for mysql-mmm.
>

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Best Pascal Hofmann (pascalhofmann) said : 		#2

It calls /usr/lib/mysql-mmm/agent/configure_ip. For example:

/usr/lib/mysql-mmm/agent/configure_ip mmm_agent eth0 192.168.0.50

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ntucker (ntucker-launchpad) said : 		#3

It looks like the send_arp code is never getting called on one of my servers when it takes on the reader role. tcpdump shows that no arp packets are being sent, and it takes >30 seconds for the role switchover to work due to arp caching on the clients. I tried manually sending the arp using a snippet of perl exactly like that in the Helpers code and it immediately cleared up the problem. I'll debug further and see if I can figure out why that code is never being hit.

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ntucker (ntucker-launchpad) said : 		#4

Thanks Pascal Hofmann, that solved my question.

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ntucker (ntucker-launchpad) said : 		#5

(it turned out to be a misconfiguration on the mysql-mmm configs (wrong interface specified), but I didn't find it until I traced through the code that actually calls 'ip')