Ergastulum: quickly finding near-optimal storage system designs

The cost of large storage systems is dominated by management costs. Typically, skilled administrators configure storage manually using rules of thumb. However, designing a storage system for a given workload is a difficult task, because there are mil- lions of possible configurations and mappings of data, and because storage system behavior is com- plex. Ergastulum is a new storage system designer that can be used both to guide administrators in their design decisions and as part of an automatic storage system management tool like Hippodrome (4). Er- gastulum generalizes the best-fit bin packing heuris- tic with randomization and backtracking to effi- ciently search through the huge number of possible design choices. Design decisions are informed by device models that estimate storage system perfor- mance. We show that Ergastulum quickly generates near-optimal storage system designs. It is faster and generates better solutions than previous tools, and it is substantially faster than an integer programming implementation that generates optimal solutions for simplified device models. We conclude that Ergastu- lum is a comprehensive solution to the storage sys- tem design problem.