Failover cluster for webserver with dynamic content ?

[Feczak Szabolcs]

No answer for days ... does it mean it can not be done correctly ?

On sze, 2005-04-20 at 12:49 +0200, Feczak Szabolcs wrote:
> On k, 2005-04-19 at 17:21 -0400, Paul Mather wrote:
> > to what you describe using geom_gate for the remote component.  See
> > ggated(8) and ggatec(8) for how to set up an use a geom_gate provider.
> 
> > Note that the geom_mirror + geom_gate synchronisation would be one-way.
> 
> Bad luck, I would like to have something that creates a layer over the
> two volume of the machines, and when this higher layer accessed both
> execute the requested operation.
> 
> Anyway one step further, my question is 
> How can I create a failover cluster with two machines 
> for a freebsd webserver with dynamic content 
> runing  apache with php, and postgresql.
> 
> I read about CARP, but more experienced people advised me to use
> DNS-LB since its more reliable with service type pings (HTTP GET) 
> than simple is the machine answers for TCP SYN. They made a point with
> that to me. 
> 
> Im trying to syncronize the postgresql database with Slony, no luck
> yet, all the examples I found describing master and slave on the
> same machine. I got slony communicate between the two, but on updates
> nothing happens on the slave. I access the master on unix socket,
> maybe other type of access needed .. hm I will see 
> 
> If on failure the switching is done with DNS-LB and the SQL is in sync
> Im nearly OK, but since I have file uploads on the webserver as well, 
> I need a shared volume which available to both of them and after
> one is out the other still has access to the data.
> 
> Maybe Im complettly wrong I have no clear ideas about what happens
> when this ... and what happens whan that ... scenarios
> 
> All I want is a higher availability with two machines than one
> and without messing up the consistency of the data of course.
> Im not after chasing nearly 100% ... the policy/expectation is 
> if one fails the other should automatically continue the 
> serving data (nearly there) where the other stopped.
> 
> If anyone did something like that, and aware of some solution without
> buying expensive HA hardware, please share us.
> Hope this is possible at all.
> 
>