Dremio stores various things under ./data, e.g. a Lucene index (in db/search) for searching in the “Jobs” UI.
catalog/ contains the actual profiles for previous job executions. If you run many queries and have a long retention period configured, it can take up quite a lot of disk space.
You can do two things to reduce the disk consumption:
Bring the cluster into administration mode and run the “dremio-admin clean” task (instructions in the helm chart) – this will introduce a cluster downtime.
Or: set jobs.max.age_in_days in Admin > Support > Support Keys to a smaller value than the default (30 days I think). It will then do a nightly cleanup (default: 01:00 in the morning, support key: job.cleanup.start_at_hour)