Synology DS720 Synology NAS Users Guide - Based on DSM 7.1 - Page 6

Chapter 2: Quick Start Guide SHR: Synology Hybrid RAID (SHR) is an automatic RAID management system designed by Synology. SHR provides fault tolerance when there are more than two drives. It is recommended for novice users because it will automatically deploy drives for the best interest of your storage space. Basic: Basic configuration is composed of only one independent drive, so it does not provide any fault tolerance or performance boost. JBOD: JBOD (Just a Bunch of Disks) configuration combines all drives into a single drive stack. Each JBOD drive is regarded as a separate and individual drive volume, so it allows easier control management of data storage. JBOD configuration does not provide any fault tolerance or performance boost. RAID 0: In contrast to JBOD, RAID 0 combines two or more drives and treats them as a single unit. In RAID 0, data are divided into blocks and split across multiple drives; therefore, the read-write speed increases with more drives added. RAID 1: RAID 1 requires at least two drives. In RAID 1, data are mirrored on all drives. Since the same data exist on all the drives in the array, the volume of the smallest member drive determines the total capacity of the array. This is the safest option to protect important data, but the write performance and capacity are relatively limited. RAID 5: RAID 5 requires at least three drives, and one of the drives is used for fault tolerance. RAID 5 stripes data blocks across multiple drives and distributes redundancy information, called parity, across all of the drives in the array. Upon failure of a single drive, the lost data can be reconstructed with the parity existing on the rest of the drives. RAID 6: RAID 6 requires at least four drives. RAID 6 features double distributed parity, so it has better data redundancy than RAID 5. However, because RAID 6 needs to write two parity blocks on all member drives, the write performance is slower than RAID 5. RAID 10: RAID 10 requires at least four drives. The drives have to be even because drives are combined into groups of two in which data is mirrored and striped. RAID 10 features the performance of RAID 0 and the data protection of RAID 1. RAID F1: RAID F1 requires at least three drives. Like RAID 5, RAID F1 implements data block striping and distributes parity data across all member drives. The only difference is that one of the drives will bear more parity information, so it will age faster, which prevents all the drives from coming to the end of their lifespan at the same time. RAID F1 is recommended for an allflash array. Notes: • RAID F1 and SHR are only available on specific models. Refer to the specifications of each model for detailed information. 03