[Linux-HA] HB general question

[MIQUET Pascal]

Thanks for your reply.

The main question is that both servers will do some specific stuff, I
mean a server will run jobs on primary and secondary.
We do not have GFS, but the same storage could be mounted on each
servers but there is no concurrent access, this is why we start with a
NFS mounted file system. As the secondary is not very loaded, I've
started the NFS export on this server.

But as I see with HeartBeat, services will run on the primary, so I need
to use a specific script to mount and then export the file system on the
VIP server.

Is GFS free ?
Does it share the file system with some concurrent access ?

Thanks for your help.

Pascal Miquet


Le mercredi 13 décembre 2006 à 14:32 +0100, Slawomir Mroczek a écrit :
> On Wed, 13 Dec 2006 10:36:32 +0100
> MIQUET Pascal <pascal.miquet at wanadoo.fr> wrote:
> 
> > I've got some other questions :
> > Can I start a specific script on activation of the HB service ?
> 
> Yes. You can use LSB (/etc/init.d/) or OCF Resource Agent
> (/usr/lib/ocf/resource.d/heartbeat) scripts.
> 
> > If the answer is yes, is there a way to know if the script runs on the
> > primary server or on the secondary secondary, and the state (I mean
> > primary is up an got services, secondary is up and primary got
> > services)
> 
> Nodes will share information about resources status. That's how HA
> works.
> 
> > Primary 192.168.1.221
> > Secondary 192.168.1.222
> > 
> > Virtual IP 192.168.1.220
> > 
> > Primary UP -> Got Virtual IP, run httpd, mount NFS file system from
> > Secondary
> > Secondary UP -> mount devices, and export NFS file system
> > 
> > Secondary DOWN !!!
> > Primary UP -> Got Virtual IP, run httpd, mount devices
> > 
> > Primary DOWN !!!
> > Secondary UP -> Got Virtual IP, run httpd, mount devices
> > 
> > 
> > Does it make sense ?
> 
> No. It does not. Why do you want to use NFS? And what device do you
> want to mount on primary node when secondary node goes down?? Have gou
> got shared storage? If so, there is no need to use NFS. Use some cluser
> filesystem such as GFS. If you don't have any shared storage there is
> problem with filesystem replication you want to mount on any node in
> cluster. Consider that scenario:
> 
> a) with shared storage (no cluserfs):
> 
> primary up -> got VIP (Virtual IP), mount devices, run httpd
> secondary up -> just wait for primary node failure
> 
> primary down
> secondary up -> takeover VIP, mount devices, run httpd
> 
> 
> b) with shared storage (cluserfs):
> 
> primary up -> got VIP (Virtual IP), mount devices, run httpd
> secondary up -> mount devices, wait for primary node failure
> 
> primary down
> secondary up -> takeover VIP, run httpd
> 
> 
> c) no shared storage:
> 
> You should use network mirrored device i.e. drdb (http://www.drdb.org)
> 
> primary up -> got VIP, drbd to primary state (active), mount, run httpd
> secondary up -> drbd to secondary state (unable to mount, but mirror
> data form primary node)
> 
> primary down
> secondary up -> takeover VIP, drbd to primary state, mount, run httpd
> 
> primary up -> drbd to secondary state (run synchronization with
> secondary node)
> secondary up -> got VIP, drbd still in primary state, run httpd
> 
> 
>