remove requirement of "first" node?

[Asad Saeed]

In our use case, we cannot easily determine from which node in our
cluster to bootstrap the "first" scalaris ring using the boot_cs
option. Is there any work being done to try keep trying to start the
ring until a quorum is reached instead of having a "first" node.

Thanks,
Asad

[Florian Schintke]

The "first" node not necessarily has to be the one started first in
time. It is just the distinction whether a started node should try
joining a ring or initiating one on its own.

So in your case, you can start all your nodes in parallel, but just
have to ensure, that a single one starts with the configuration of a
first node. Does that help to ease your szenario?

Florian

[Asad Saeed]

[Asad Saeed]

This would not work in a failure scenario. Lets say you have a 5 node
cluster. Due to a power outage, the entire cluster restarts, but the
node designated for initializing the ring fails when the power comes
back. The other 4 nodes will just wait indefinitely upon the failed
node.

With keeping with the ability to dynamically add nodes. Could a
feature be added where the well known "seed" peers are required to
have a quorum when initializing a ring. This would allow for a ring
only to be initialized once a cluster has reached quorum and does not
have a single point of failure during startup. With this mechanism
other nodes could still be dynamically added. without having to change
configurations, (cluster would be dependent on seed ring having
quorum).

Asad

[Florian Schintke]

Hi,

good idea. Thanks.

We implemented that as of r1735. Just start all your nodes with
bin/quorum_node.sh. When a quorum of the 'known_hosts' becomes
available, the system gets started.

Thorsten & Florian

[Asad Saeed]

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Florian