[Linuxha-users] Update on Linuxha.net 0.8.3 progress

[Simon Edwards]

Hello all,
	Just a quick update on progress of the Linuxha.net 0.8.3 release. I am
hoping this will be released in the next day or so. However rather than
the online file system size change support 0.8.3 will be shipped with a
completely new networking sub-system. I deemed these changes necessary
due to several limitations of the previous code, including;

[1] No clear division between cluster and application configuration
files for the cluster network topology settings.

[2] The fail-over response was taking too long (up to 3 seconds).

[3] The code made use of multiple IP addresses on the same subnet -
which is not considered a good thing.

[4] The application was only able to apply IP addresses on one card and
on one subnet on that card.

The new code addresses all these problems and overall results in
improved fail-over times, reduced code size and a more logical
separation between application and cluster configuration information.

These changes are handled by having a separate network monitoring daemon
which is always running when the main cluster daemon runs on a node. 

How does this all affect existing applications? Well changes with
existing configurations of both the cluster and application
configuration files will be necessary - but the changes are not huge,
for example in the cluster configuration file you now define "networks"
- groups of cards that can provide IP addresses on the same subnet, i.e;

        <node>
                <name>server1.linuxha.net</name>
                <network name="main" cards="eth0,eth1"/>
                <network name="drbd" cards="eth2"/>
        </node>
        <node>
                <name>server2.linuxha.net</name>
                <network name="main" cards="eth0,eth1"/>
                <network name="drbd" cards="eth2"/>
        </node>

It is possible to define 0,1 or more networks and call them whatever you
wish (here called "main" and "drbd").

In the application configuration file the network section might look
like the following;

        <networks>
                <network net="main" ip="192.168.0.102,103"
                        checklist="192.168.0.1" checkpercent="100"
                        pingtype="icmp" pingtimeout="3"/>
                <network net="drbd" ip="192.168.100.12"/>
        </networks>


In the above example the application hosted two IP addresses on the
"main" network and actually one on the "drbd" network. Now an
application can defined 0, 1 or more IP addresses - and these can be on
multiple networks as well. Notice that you do not define the cards that
can be used - all topology information is now handled at the cluster
level to keep the application configuration as straightforward as
possible.

The above is a sample of the changes - one or two other changes will be
necessary but shortly after the code is released I'll provide suitable
documentation to migrate.

Although a big change I believed it was necessary to ensure that the
version 1.0.0 reaches the quality I wish it to.

Regards,
Simon.