[prev in list] [next in list] [prev in thread] [next in thread] 

List:       linux-ha-dev
Subject:    Re: [Linux-ha-dev] Starting heartbeat when interfaces are down
From:       Dejan Muhamedagic <dejanmm () fastmail ! fm>
Date:       2007-10-24 10:29:02
Message-ID: 20071024102858.GA25331 () rondo ! suse ! de
[Download RAW message or body]

Hi,

On Tue, Oct 23, 2007 at 10:14:50PM -0400, Graham, Simon wrote:
> > 
> > And indeed, the cluster does come up - without a node.  A more
> accurate
> > summation is that "a single node in the cluster doesn't come up".  So,
> > the _cluster_ does recover from this error.  It just does it without
> > that node.  So, service is not interrupted.
> > 
> 
> At the end of the day then, I think my problem comes down to the fact
> that I am not using static IP addresses for the NICs -- I know you
> consider the use of DHCP (and also, I would guess zeroconf) addresses a
> bad thing - however, consider the case where one is trying to automate
> the cluster config/setup - in this case, the actual IP addresses used
> for the NIC are completely irrelevant to anyone other than the hb code
> (because users of the cluster should ONLY be using the cluster alias
> address).
> 
> If you use DHCP/Zeroconf then if a NIC does not have link at boot time,
> it will not get an address assigned and HB will refuse to start with
> this error:
> 
> Oct 17 05:41:47 heartbeat[10189]: 2007/10/17_05:41:49 ERROR: glib: Get
> broadcast for interface eth1 failed: Cannot assign requested address 
> Oct 17 05:41:47 heartbeat[10189]: 2007/10/17_05:41:49 ERROR: glib: IP
> interface [eth1] does not exist 
> Oct 17 05:41:47 heartbeat[10189]: 2007/10/17_05:41:49 ERROR: Illegal
> bcast [UDP/IP broadcast] in config file [eth1] 
> Oct 17 05:41:47 heartbeat[10189]: 2007/10/17_05:41:49 ERROR: Heartbeat
> not started: configuration error.
> Oct 17 05:41:47 heartbeat[10189]: 2007/10/17_05:41:49 ERROR:
> Configuration error, heartbeat not started.
> 
> This actually can lead to HB not starting anywhere (consider the case of
> a two node cluster with a direct cable connect for one of the NICs -- if
> one node is powered off, then the other one will not have link on the
> NIC and therefore will not assign an address)
> 
> I'd be interested in more discussion on why DHCP/Zeroconf is considered
> anathema.

I wouldn't say that it is an anathema. But, if you want to use
DHCP to provide a static address then make sure that DHCP is
always available. How do you expect to have a high availabitlity
solution which depends on DHCP and DHCP is not there?

> I'd also be interested in knowing if anyone is working on supporting IP
> V6 broadcast/multicast for the hb comms links (in which case a static
> address can be allocated with no configuration required)

Not to my knowledge. But that should be soon addressed.

Thanks,

Dejan

>  
> > This is the rationale for this behavior.  It's not perfect behavior,
> > but
> > it's not completely irrational either...
> > 
> > --
> >     Alan Robertson <alanr@unix.sh>
> 
> Thanks for the explanation - it helps a lot and is exactly what I was
> looking for.
> Simon
> _______________________________________________________
> Linux-HA-Dev: Linux-HA-Dev@lists.linux-ha.org
> http://lists.linux-ha.org/mailman/listinfo/linux-ha-dev
> Home Page: http://linux-ha.org/
_______________________________________________________
Linux-HA-Dev: Linux-HA-Dev@lists.linux-ha.org
http://lists.linux-ha.org/mailman/listinfo/linux-ha-dev
Home Page: http://linux-ha.org/
[prev in list] [next in list] [prev in thread] [next in thread]