Which database salesforce using to store the data?

@rajeshediga Nice question. I got curious as well, and found the following on http://www.dbms2.com/2011/09/15/database-architecture-salesforce-com-force-com-and-database/

salesforce.com’s data is stored in Oracle

Besides Oracle, salesforce uses at least a file system and a RAM-based data store.

Please share your findings as well.