A main memory database system holds all data in volatile semiconductor memory. The crash recovery manager of such a system logs changes to disk and periodically checkpoints the database to non-volatile storage. The manager is different from that of a disk-based system because after a failure the main memory and not the disk must be restored to a consistent state. Furthermore, the performance of the recovery manager is more critical since it is the only component of the system that performs expensive I/O operations. In this paper we study the algorithms for the performing main memory crash recovery. Their performance is compared via a detailed model of the critical resources for this environment: CPU overhead and disk bandwidth. The performance results suggest a set of "rules of thumb" for selecting a crash recovery strategy.