STORAGEDB: Enhancing the Storage Sub-System with DBMS Functionalities

This paper proposes STORAGEDB: a paradigm for implementing storage virtualation using databases. It describes details for storing the logical-to-physical mapping information as tables within the database; handling the incoming I/O requests of the application as database queries; bookkeeping of the I/O operations as database transactions. In addition, STORAGEDB uses built-in DBMS features to support storage virtualization functionalities; as an example we describe how online table space migration can be used to support reallocation of logical disks. Finally, we describe our modifications to a traditional RDBMS implementation, in order to make it light-weight. Improving the performance of a traditional DBMS is critical for the acceptance of STORAGEDB since the performace overheads are considered a primary challenge in replacing existing storage virtualization engines. Our current lightweight RDBMS has a 19 times shorter invocation path length than the original. In comparision to the open-source virtualization software, namely LVM, the extra cost of STORAGEDB is within 20% of LVM in trace-driven tests. (unlike STORAGEDB, LVMdid not have logging overhead). We consider these initial results as the "stepping stone" in the paradigm of applying databases for storage virtualization.