LGTM Enterprise 1.22.2

Moving control pool components

Most LGTM Enterprise systems start with a single machine hosting all the components for the control pool. These components initially store their data in the default control pool data directory: /var/lib/lgtm.

As the system grows, you may want to move some components onto dedicated machines, for example, the two main storage components: the file store and the database. You may also wish to move the control pool data directory.

You can relocate individual components as follows:

  1. Take down LGTM using lgtm-down.
  2. Back up LGTM using your normal method.
  3. Update the cluster configuration:
    1. Edit the lgtm-cluster-config.yml file and specify the new hosts for the components you want to move, and/or change the data_path.
    2. Generate updated files for the cluster configuration using lgtm-config-gen.jar.
    3. Deploy the new configuration on each machine in the control pool, including the new host machines.
  4. Restore the components you want to move to the new host machines and/or move the control data directory.
  5. Bring LGTM back up using lgtm-up.
  6. Check that everything is working as expected. For example, check that you can log in as a user, view data for a project, and run a simple query.
  7. Delete any unwanted data from the original location for the components that you moved.

For more detailed information about the processes outlined in these steps, see:

Example

A system is initially set up with the control pool hosted on a single machine. As the system expands, the configuration is updated to change: the location of the control pool data directory, and the host machines for the database and file store. This is an excerpt from the updated lgtm-cluster-config.yml file, with the changes highlighted:

data_path: "/lgtm/control-pool/data"

coordinator:

  hostname: "lgtm"

database:

  hostname: "lgtm-db"

file_storage:

  hostname: "lgtm-files"

queue:

  hostname: "lgtm"

search:

  hostname: "lgtm"

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