Scaling

Being based on Aegir, DevShop has two methods for scaling a site's servers:

Web Packs

Web Packs use NFS to sync the entire /var/aegir/projects folder to a group of servers.

For more information on Web Packs, see the Aegir documentation page at http://aegir.readthedocs.io/en/3.x/usage/servers/clustering/#using-the-pack-module.

Pros:

• Depending on where your mount points are, all codebases for all environments are shared with every server in the group. This makes setup & management simpler.

• No need to create new NFS shares per environment.

Cons:

• Extra steps needed to install NFS client & server.

• Introduces a "single point of failure" if the NFS system fails.

• Storing executable code on NFS has been reported to result in poor performance. (See articles like NFS performance degredation and Drupal on NFS

• Special configuration needed to mitigate performance issues.

• All codebases are shared with every server in the group. This might not be ideal.

• Manual setup of load balancer is needed.

Web Clusters

Web Clusters uses Rsync to copy an environment's files to a group of servers.

For more information on Web Clusters, see the documentation page at http://aegir.readthedocs.io/en/3.x/usage/servers/clustering/#using-the-cluster-module.

Pros:

• Simpler to use out of the box: no additional packages needed.

• RSync is a simple and reliable of delivering code to the servers.

• Source code is on disk, no performance overhead.

• No single point of failure.

Cons:

• Drupal files folder is not synced across servers out of the box. Requires a manual solution.

• Shared files folder needs to be setup for every environment.

• Manual setup of load balancer is needed.

See https://groups.drupal.org/node/291688 for a discussion on files folder sharing solutions.