[Linux-cluster] Re: cman multihome setup deprecated?

[Patrick Caulfield]

Axel Thimm wrote:
> On Mon, Nov 07, 2005 at 03:22:04PM +0000, Patrick Caulfield wrote:
> 
>>Axel Thimm wrote:
>>
>>>Is this functionality deprecated and to be removed in a future update?
>>>Or does it need some work to be republished?
>>>
>>>What is the recommended precedure for having a dedicated cluster
>>>network with a failover setup over a secondary network? E.g. I have
>>>all cluster nodes connected over two network, the client ("LAN")
>>>network, and a dedicated cluster network ("cluster-net").
>>>
>>>What I'd like to achive it to have high-performance by allowing
>>>cman/dlm to have its own network, but also high-availablity by using
>>>the "LAN" network when the "cluster-net" fails, e.g. broken cable or
>>>broken switch.
>>
>>"deprecated" isn't quite the right word! But I'm not sure what is.
> 
> 
> "in works" ? :)

Something like that, yes



>>As it stands, cman in RHEL4 supports multihome. The problem is that the DLM
>>doesn't so it's not much use in most environments.
> 
> 
> So what would be the impact if the primary network breaks down? cman
> continues to operate happily, e.g. the heartbeat works, the cluster
> remains quorate etc., but GFS cannot operate its locks anymore?
> 
> Would that harm more than it would help? I.e. should I better
> implement multihoming on a lower level, e.g. a dynamic router on each
> node?

It's not useful - that's why the multihome capability in cman is
played down or denied.

So, if you wanted do do something smarter than bonded interfaces with redundant
switches then you'll have to do some smart routing/switching/bonding, yes.

> 
>>At the head of CVS, cman does not support multihome (though this should get
>>added to AIS soon-ish) but the transport layer of the DLM does :)
> 
> 
> That's for RHEL5 I guess :)

Certainly.

> 
>>Currently for failover we recommend the bonding network device which doesn't
>>achieve what you want, I agree.
> 

-- 

patrick