It is a drop-in replacement for FileStorage and ZEO.There is a simple way to convert FileStorage to RelStorage and back again. You can also convert a RelStorage instance to a different relational database.Designed for high volume sites: multiple ZODB instances can share the same database. This is similar to ZEO, but RelStorage does not require ZEO.According to some tests, RelStorage handles high concurrency better than the standard combination of ZEO and FileStorage.Whereas FileStorage takes longer to start as the database grows due to an in-memory index of all objects, RelStorage starts quickly regardless of database size.Supports undo, packing, and filesystem-based ZODB blobs.Both history-preserving and history-free storage are available.Capable of failover to replicated SQL databases.Free, open source (ZPL 2.1)