you don't have any issues on database. The ELM database takes almost 500 Gb in ordert to get working.
You can migrate many times from a storage to another; the ELM is mounted on /elm_storage directory.
but the strange thing for me is that I've reserved 500 GB for that db on the storage and the data on that db are less than 200 Kb, not almost 500 GB.
Can you check on your SIEM how may GB is taking your exported DB?
you must reserve almost 500 Gb because it's a ELM request. The more data you collect, the greater is the db.