[DRBD-user] DRBD + Heartbeat + 1 eth + 1 serial

Matteo Campana matteo.campana at klarya.it
Fri Sep 28 16:46:41 CEST 2007

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

Lars Ellenberg ha scritto:
> On Thu, Sep 27, 2007 at 01:06:39PM +0200, Matteo Campana wrote:
>> Hi Lars and all the guys in ML :).
>> My problem is to understand the behaviur of my HA system: I have read in 
>> the documentation about heartbeat that at least 2 channels of 
>> communication between 2 nodes are required to preserve the system from 
>> the "split brain" problem (in my system I have 1 ethernet +  1 serial).
>> But....in my tests I see however  that DRBD says the "infamous" :) 
>> message "split-brain detected" ecc.. .
>> My test:
>>    * I disconnect primary node from the ethernet
>>    * secondary ----> primary  (ok)
>>    * I reconnect primary
>>    * secondary still remain primary (ok for my config)
>>    * the problem is that the two nodes are standalone and not
>>      re-syncronize theirs drbd partition.
>> DRBD does not use also the serial channel in order to communicate 
>> between the nodes?
> um. it does use the heartbeat communication infrastructure,
> if you configure the "outdate-peer handler", in which case it had
> outdated the other node, before you try to make it primary,
> thus preventing you from going online with stale data.

I need to recompile heartbeat to use the "outdate-peer" plugin?
(currently I'm using the heartbeat package for Debian).

> or did you just suggest that we should mirror block io
> via 9600 baud serial line?

Oh...no Lars :):)
But it was no clear for me how to tell drbd to use heartbeat 
communication, that is the "outdate-peer handler" tips that you have 
explain before.

Thank you!

* Ing. Matteo Campana
System Engineer

Klarya s.r.l.*

**Open Source IP Communications*

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