On 22 Aug 2012, at 12:24, David Lang <[email protected]> wrote:
> I believe that in pacemaker you can configure a resource to run on
> multiple systems in an active/active configuration.

Okay, how does one designate that resources are in an active/active 
configuration in Pacemaker?

> But I don't know how you would combine that with a separate IP address
> resource in a active/failover configuration (you would have to add a
> dependancy to the IP resource to say that it can only run on a node that
> has an active Apache resource)
>
> The trouble is that the resource management spec requires that the
> startup script be able to run the sequence
> 
> start
> monitor
> start
> monitor
> stop
> monitor
> stop
> monitor
> 
> and get the correct monitor output (started or stopped) each time. If
> you change stop to be a noop, you also need to tinker with monitor so
> that it returns a "stopped" status if heartbeat doesn't want the process
> running, but you still need to properly detect if Apache has stopped
> when heartbeat wants it to be running.

Yes, those are my challenges...
 
> You also have the problem that by doing this, you have elimianted any way for
> the system to do a graceful shutdown of Apache when you want to shut the 
> entire
> system down (the system will tell heartbeat to stop, heartbeat will tell 
> Apache
> to stop, and you want to configure Apache to ignore this)

Without having any resource script to inspect for the LSB apache resource, I 
couldn't say for sure, but I imagined that I would be able to null out the stop 
operation only in cases of an active node becoming passive (speaking in terms 
of the IP resource here).  It would (in my hypothetical scenario) still stop 
apache on shutdown and it would still monitor it for failure, thus triggering 
the IP resource to fail over.

> you are probably better of creating a heartbeat resource along the lines
> of "iamhealthy" that toggles the state of some status file and reports
> it's status based on that file. Then you setup other monitoring of the
> box that overrides this status file if it thinks that there is anything
> wrong. This monitoring can be that Apache dies, that network
> connectivity dies, that the box is out of disk space, is out of memory,
> or any other health checks that you find that you want.

Sounds a little more... complicated... than I was looking for.  I guess this is 
just not possible without modification past the point where my corporate 
overlords will let me go.  I suppose we can just live with apache stopping on 
the passive node and having to start up again when it becomes active again. :/

Thanks.

> David Lang

Jon Heese
Systems Administrator
Weld County Computer Services
ACS Government Systems, Inc., A Xerox Company
tel: 970-304-6570 x2552
[email protected]

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