Increasing promote/publish speed in Satellite 6 by compacting mongoDB

Issue

Satellite 6 backend system Pulp uses MongoDB database for storing repository metadata. As more and more data files are added by MongoDB, the total database size grows from a default 3 gigabytes up to tens or hundreds of gigabytes. Data is fragmented and promotion or publishing speed decreases.

This can be improved by bringing the Satellite 6 instance down and performing a MongoDB maintenance operation called "database repair". Our numbers show that the size of the database decreases drastically (around 50 %) and promote (or publish) operations are faster by 60-80 %.

The same steps from this Solution can also be applied to the Capsule server, where the impact to performance (which has not been measured) is expected to be smaller, but still visible (in cases of already fragmented data in MongoDB).