The Log Insight virtual appliance uses a minimum of 100GB of storage for incoming logs.

When the volume of logs imported into Log Insight reaches the 100GB limit, old log messages are automatically and periodically retired on a first-come-first-retired basis. To preserve old messages, you can enable the archiving feature of Log Insight. See Enable or Disable Data Archiving in Log Insight.

Data stored by Log Insight is immutable. After a log has been imported, it cannot be removed until it is automatically retired.