Take a look at DRBD.  You can define it as one of the resources that
"heartbeat" maintains HA state for.  We use it in our active/passive
pairs, but newer versions of DRBD support active/active. Of course you
need to have a filesystem (GFS, OCFS) that can handle active/active
on shared storage (DRBD acts like shared storage in an active/active setup).
If you are a user of CentOS, you can use RedHat's clustering system
to implement an active/active cluster using via GFS on DRBD.

On Thu, Apr 17, 2008 at 11:45:34AM +0200, Gregory Machin wrote:
> Hi
> I'm looking for a way to mirror data between to servers.
> Where both servers have the same services configured but only some are
> running on the one
> and the remaining are running on the other .. Should one server fail all
> the services become active
> on the one server , and once the issue is resolved and the server is
> back online the services are split up again. This Is easy enough with HA
> etc..
> But I need both servers to mirror each others data, in real time  so
> should  one  go down the other is ready
> to take over, and the process is transparent to the clients / users. And
> when the failed server is started up
> again the data is resynchronized  then the services are brought  on line
> again.
>
> Eg server 1 provides smtp , pop3 , imap
>   server 2 provides mysql, http, dns
>
> If server 1 fails or goes off line server to takes over all roles mysql,
> http, dns and smtp , pop3 , imap
> If server 2 files or goes off line server to takes over all roles smtp ,
> pop3 , imap and mysql, http, dns
> so both servers have to be up to date with each others data, when the
> off line  server comes back online
> It needs to syn the difference for all the services that may have
> changed mysql, http, dns, smtp, pop3, imap
> and thus both servers resume normal services.
>
>
> Can ocfs2 do this ?
>
> -- 
> Gregory Machin
> CT-Net
> www.ct-net.org
> greg_at_ct-net.org
> phone : +27 12 379 3497
> fax   : +27 12 379 4113
> Cell  : +27 72 524 8096
>
> humans do not use the address
> below its for trapping spam.
> spamtrap  imasucker_at_ct-net.org
>
>

-- 
James R. Leu
jleu_at_mindspring.com