High-availability cluster and samba

Frederic Dubuy frederic.dubuy at medasys-digital-systems.fr
Mon Feb 7 09:52:37 GMT 2000

Nicolas Williams (Nicolas.Williams at wdr.com) s'exprimait ainsi :

> Hmmmm.
> I don't see what that script does as far as running two Samba servers
> on the same host, each binding to a different set of IP addresses and
> each using a different set of NetBIOS names and aliases.
> Or do you only support one personality per host at any time?
> Where I work we have a Samba HA system built on top of Solaris +
> Veritas HA.
> Veritas HA is based on the takeover-the-failed-host's-IP-addresses-and-
> services model.

It's exactly the same principle we used, the
takeover-the-failed-host's-IP-addresses-and-services as you call it. 
> But note that when you take over a failed host's IP addresses you're not
> changing the resolution of the failed host's _names_ to a different set
> of IP addresses.

Sorry if I wasn't that clear (perhaps 'cause of my approximate english). The
situation was we had two servers :
- one called cluster1, with IP
- one called cluster2, with IP

As we wanted transparency for clients, we couldn't provide a service sometimes
called cluster1 sometimes cluster2, as it may be perturbating and prevents
permanent connections. That's why we used a third IP address (
associated with a third name : cluster3. The server running samba gets both.
When it fails, this IP address is used by the second server.
The problem is that samba tends to announce on all its interfaces (don't flame
me if it's not really true, I didn't look at the source code for that. It's
just an observation), and a windows client doesn't always see 'cluster3' as we
wanted to, but also cluster1 or cluster2. That's why the 'interfaces'
parameter is limited to the 'virtual' IP address, and the Netbios
name set to cluster3 (so the two smb.conf are ABSOLUTELY identical!). Using this
 parameters windows clients see only one server, always called cluster3. 
The use of a Wine server and a remote announce to it shortens the latency time
during which some clients don't see the server any more.



Frédéric Dubuy <frederic.dubuy at medasys-digital-systems.fr>
Centre de compétences Logiciels Libres - Medasys
Tel : (33) Fax : (33)

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