Jet is our database backend for Plastic SCM, it's super fast and requires less maintenance than MySql and SQLServer. Jet is a file system database, and you don't need to install third party software to support it, everything comes inside the Plastic SCM Server.
Read the history of the Jet backend: http://blog.plasticscm.com/2018/06/story-of-jet-fast-repo-storage.html
How to migrate your current repositories
The new Plastic SCM Server WebAdmin interface supports the database backend migration. Browse "serverName:7178" and select "Repository storage":
The "Repository Storage" will show your current database backend. The picture below shows "MySQL" and all the related configuration. Notice there's a "Change storage" button, click it to start the migration wizard.
"Jet" is the default option, choose a custom "Database path" is you want to store the database files at a custom directory.
The "Change storage" button will start the migration operation.
Once the migration ends, the Plastic SCM starts using the Jet backend, no restart needed.