We present FlashStorageSim, an SSD architecture performance model for data center servers, validated with an enterprise SSD. In addition to the SSD controller, SSD organization, and flash devices, FlashStorageSim models the host interface (e.g., SATA, PCIe, DDR). This allows users to explore non-traditional SSD use cases. We also implement mechanisms to improve simulation speed, which is shown to reduce simulation time by more than 7X. We show how FlashStorageSim can help researchers understand SSD design decisions.