What is ZFS?
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) to accelerate READ access (SSDs can also be used to increase the performance of WRITE access). ZFS Intent Log (ZIL) and Separate Intent Log (Slog) are both written to SSDs. EonNAS 3000 series* storage systems support SSD to improve the performance of applications with frequent random READ operations.
* 3310/3510 series