The SigParser On Premise Engine uses some local storage.

We suggest at least 50GB of storage to provide enough space for the operating system, about 200MBs of logs and up to 10GB of temporary storage.

Our logs are set to automatically rollover and delete old logs that are stored locally on the server. This makes it so the logs never consume too much storage.

The 10GB of temporary storage is used if the SigParser cloud API ever goes down temporarily or your API key stops working or some other transient issue that might need to be addressed. In this case the On Premise Engine stores the data it collected (meta data, not email bodies or attachments) for retrying later.