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Creating a Pioreactor cluster

Pioreactors are able to be used as individual units, or in concert with other Pioreactors. In either case, a Pioreactor needs to be assigned as a leader. The leader unit controls other Pioreactors (and that may include itself), stores the database, hosts the web interface, and is the interface between users and the hardware.

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When you set up your first Pioreactor using our software installation guide, your Pioreactor was set up to be a leader already. You only need one leader in a Pioreactor cluster.

A leader will communicate and control all the workers (non-leader Pioreactors) in the inventory. The inventory is a list of workers in your cluster, defined in the section cluster.inventory in the config.ini.

Workers can be active (available for running activities and housing cultures), or inactive. This is set with 1 or 0 respectively in the cluster.inventory section.

When you want to remove a Pioreactor from your cluster, you can remove it from the list in available inventory in cluster.inventory section in config.ini.

Possible cluster topologies

A cluster can be made up of a single Pioreactor, or can be scaled to as many Pioreactors as you have. This gives us a few different possible topologies of what your cluster of Pioreactor(s) might look like.

Single Pioreactor

The simplest topology is when you have a single Pioreactor, and so by default the leader is the only worker.

Cluster, and leader is a worker

When you have multiple Pioreactors, you can nominate one to be the leader node, and retain it as a worker, too:

leader is also a worker in the cluster

Cluster, and leader is not a worker

You can also choose not to have the leader be a worker. This is useful if you have a spare Raspberry Pi without the Pioreactor hardware, or the number of Pioreactors grows large and you wish to keep one out of the inventory to focus on being a leader only.

leader not worker

How to edit roles

To tell the cluster which computer is the leader, you edit the config.ini's leader_hostname section (under cluster.topology):

where to edit the leader

Inventory is assigned in config.ini under cluster.inventory:

Adding new workers

See the instructions here to add new workers to your cluster.