ZFS is a combined file system and logical volume manager. The features of ZFS include data integrity verification against data corruption modes, support for high storage capacities, integration of the concepts of file system and volume management, snapshots and copy-on-write clones, continuous integrity checking and automatic repair. ZFS Hybrid Storage Pool ZFS provides users with a Hybrid Storage Pool system by utilizing advantages of different storage types, including RAM, SSD (Solid State Disk) and hard drive. A hybrid storage pool consists of the following three elements: ZIL (ZFS Intent Log), Read/Write cache pool, and a high capacity pool. ZFS adopts the Adaptive Replacement Cache (ARC) mechanism, which temporarily stores operating data in RAM to improve performance. The cache data is controlled via two parameters: Most Recently Used (MRU) and Most Frequently Used (MFU). The second level cache, which is called Level-2 ARC (L2ARC), uses flash memory (such as SSD