RAID, the abbreviation of Redundant Array of Independent Disks, is a technological combination of multiple physical disk drives to appear as one single logical storage unit on the operating system layer. The central concept of RAID is to make uses of multiple disk drives for capacity multiplying, performance boosting, and/or data backup. With the rapid growth in cloud storage and networking throughputs, RAID is widely applied in servers and network appliances for efficient data and storage management. Today, there are various types of RAID applications and this document is going to focus on RAID-0, RAID-1 and RAID-5, which are the types often requested by our clients.
RAID-0: Data Stripping
RAID-0 requires at least two physical disk drives and the total capacity is the sum of all available storage devices. RAID-0 is a data stripping mode that distributes data contents equally or almost equally among all storage devices in the RAID set. This will lead to an obvious read and write performance boost. In fact, RAID-0 is considered one of the highest read and write enhancements among all RAID types. However, RAID-0 lacks mirroring nor parity check so that there is no fault tolerance of data transferring failure which leads to a comparably higher risk of data loss, when comparing to other RAID modes.
RAID-1: Data Mirroring
Like RAID-0, RAID-1 requires two or more physical disk drives to operate. In the mirroring mode with two available storage devices, one disk drive is functioning as the main storage for read and write operations, while another is used as a mirror. The mirroring disk will store the identical data contents as the backup for system owners. This is considered as the highest fault tolerance RAID type.
However, the total capacity in RAID-1 is the total capacity of the operating disk drive. In a two-disk scenario, the capacity of one disk drive is sacrificed for mirroring in order to backup data when the functioning device fails. For example, with two 256GB disk drives present, the total useable capacity is still 256GB in RAID-1 mode. The other 256GB is for mirroring the data. When one disk drive fails, the mirroring one will take its place to remain operations. Though with high fault tolerance, system owners pay higher cost in capacity usages.
On the other hand, due to the effort in mirroring, read and write performance is slower than many other RAID types.
RAID-5: Parity Check
Different from RAID-0 and RAID-1, RAID requires 3 or more disk drives to function. RAID is a balance of RAID-0 and RAID-1 and also parity check. Regarding total usable capacity, RAID-5 sacrifices the capacity of one disk drive. For instance, when forming a RAID-5 with three 256GB disk drive, the total useable capacity is 2 x 256GB, which will be 512GB. One disk drive is reserved for fault tolerance.
The central concept of RAID-5 is based on parity check. In this mode, data contents are distributed and stored in disk drives within the set by parity. When one disk is down, the system owner can retrieve the data based on the parity. As said earlier, RAID-5 is a balance of RAID-0 and RAID-1. RAID-5 offers considerable data reliability but not as guaranteed as RAID-1. Performance wise, RAID-5 delivers significant boost in read but slower write due to parity check operation. With the need of additional disk drives, RAID-5 provides more total capacity than RAID-1.
*P stands for parity.
Lanner’s RAID Solutions
To respond clients’ requests for high capacity and other data functions, Lanner offers both hardware and software RAID solutions. The software RAID implementations are normally operating system based and pre-programmed in the CPU. Lanner’s software-based RAID include Windows Volume Management, Linux Volume Manager and Intel Matrix Storage Manager.
Lanner also offers hardware-based RAID implementations include RAID cards and/or hot-swappable HDD/SSD trays. Lanner recommends clients to implement hardware-based RAID implementations for higher reliability and performance.
For details about our hardware and software RAID solutions, please contact Lanner representatives.