RAID stands for “Redundant Array of Independent Disks” or “Redundant Array of Inexpensive Disks,” which is a data storage technology that combines multiple physical disks into one logical unit. The primary purpose of RAID is to improve performance, availability, and/or redundancy of data.
In RAID, grouped physical disks work together to increase data read and write speeds, or provide protection against disk failure. Data is broken down into small blocks distributed across different disks in the array, which allows parallel access and usage of data, thereby increasing the speed of I/O operations.
There are several different RAID levels (such as RAID 0, RAID 1, RAID 5, RAID 6, RAID 10, etc.), each with different ways of working and characteristics. Some RAID levels offer a higher level of redundancy to protect data from disk failure, while others focus on performance.
Commonly used RAID types
Sometypes of RAID are commonly used in computing environments. Among them:
- RAID 0 (Striping): RAID 0 splits data alternately between two or more disks, improving overall read/write speeds. However, RAID 0 does not provide redundancy of data, meaning that if one disk fails, all data on that array is lost.
- RAID 1 (Mirroring): RAID 1 uses two disks (at a minimum) to make identical copies from one disk to another. It provides full redundancies, so that if one of the disks is damaged, the data can still be accessed from the still functioning disk.
- RAID 5: RAID 5 uses a minimum of three or more disks to provide a combination of striping and parity. Data is partitioned and parity is calculated and distributed across disks. If one disk is damaged, the data can be reconstructed from the parity information stored on the other disk.
- RAID 6: Similar to RAID 5, RAID 6 also uses striping and parity, but with two parities that make it possible to address failures of up to two disks simultaneously. It provides a higher level of redundancy than RAID 5.
- RAID 10 (RAID 1+0): RAID 10 combines the features of RAID 1 (mirroring) and RAID 0 (striping). At least four disks are required to create RAID 10. The data is split into two mirrored disk sets, and then the data is striped in each mirror set.
Of all the RAID types above, RAID 5 and RAID 6 have become popular choices in business environments because they provide a combination of performance and data redundancy. RAID 10 is also quite popular because it provides a high level of redundancy with good performance. However, the right RAID choice will largely depend on the specific needs of each situation, such as budget availability, required storage capacity, desired redundancy level, and expected performance.
Advantages of RAID
RAID (Redundant Array of Independent Disks) has various advantages that make it a popular choice in computing environments, especially in critical data storage systems.
Although RAID has many advantages, it is important to remember that RAID is not a perfect solution. RAID only protects against disk failure, not other problems that can cause data loss such as natural disasters, malware attacks, or user error.
Regular data backups are still necessary to protect data end-to-end. Here are some of the advantages of RAID:
- Data Redundancy: Multiple RAID levels (such as RAID 1, RAID 5, RAID 6, RAID 10) provide data redundancies. With redundancy, data is stored or copied across multiple disks, so that if one disk fails, it can still be accessed from another working disk. This helps protect data from loss due to disk failure.
- Increased Performance: Some RAID levels (especially RAID 0) use striping techniques, where data is partitioned and distributed across multiple disks. This increases the overall read and write speed of data because data access can be done in parallel. In some situations, RAID can provide much higher performance compared to using a single disk.
- Scalability: RAID makes it possible to combine multiple physical disks into one logical unit, thereby increasing storage capacity efficiently. If the storage capacity is insufficient, you can easily add more disks into the RAID array.
- High Data Availability: RAID with high redundancies (such as RAID 6 or RAID 10) can increase data availability. Even if some disks fail, data can still be accessed and the system can continue to operate.
- Fast Data Recovery: If there is a disk failure on RAID with redundancies, data recovery is usually faster than recovery from backups because the data is still on the disk that is still working and can be accessed immediately.
- Disk Usage Efficiency: Some RAID levels, such as RAID 5 or RAID 6, use parity to store redundant data. This allows efficient use of storage space as not all disks are required to store the same data.
- RAID Hot-Swapping: Some RAID systems support hot-swapping, which allows replacement of damaged disks without shutting down the RAID system. This reduces downtime and simplifies the maintenance process.