RAID is decrypted as “Redundant Array of Independent Disks” (backup array of independent disks). Under the RAID-array understand the union of several physical disks into one logical. The OS interacts with the RAID as one drive, despite the fact that it consists of several hard drives. Arrays are software and hardware. The first are combined with the help of the OS, the second – before the OS is loaded, with the help of special utilities.
What is RAID 0, 1, 5 and 10?
Hard disks, combined into arrays, give an advantage in data writing / reading speed, have higher fault tolerance (data recovery from RAID is not required) and a level of security. To understand how this happens, consider the main types of RAID-arrays, how they are formed, as well as the purpose of their use.
- RAID-0. This array is also called “Stripe” or “Ribbon.” Several hard drives here are combined by sequential summation of volumes. Two 500 GB disks are perceived as one, with a capacity of 1000 GB, – the speed of writing and reading information increases twice. The more disks in such an array, the faster it works. The disadvantage of RAID-0 is the lack of fault tolerance: when a single disk fails, the entire array does not work. As a result, you have to restore the entire RAID array.
- RAID-1. It is also called “Mirror”. Here several hard drives are combined by parallel merging. Of the two 500 GB disks, one 500 GB disk is also obtained. The speed will remain the same (like a single 500 GB disc). There is no advantage in speed of such an array, but it provides high fault tolerance: when a single hard disk fails, a full take of information remains on the second disk, which is used to restore the entire contents of the array. However, it is worth remembering that if the user deletes information purposefully, it is deleted from all disks simultaneously, and recovery from RAID 1 will be more difficult.
- RAID-5. This array is an advanced version of RAID-0. Several hard drives are combined into a RAID-0 array. On one of the disks, service information is stored, with the help of which any of the disks are restored in the event of their failure. The result is a higher level of security, with the same read speed as on RAID-0, although writing is performed at a slower rate, since additional time is spent on writing the checksum. An array is created from a minimum of 3 disks, which guarantees that the recovery of the necessary data of RAID 5 will be quite fast. RAID-5 does not have protection against simultaneous errors on different disks.
- RAID-10. It is also called RAID 1 + 0. The RAID-10 array is conceived as a symbiosis of RAID-1 and RAID-0 and combines the advantages of both options, namely, high speed and fault tolerance (data recovery from RAID 10 is performed by analogy with RAID-0). To create it requires a minimum of four drives. There are other varieties of the main arrays – they are used only to increase the level of fault tolerance or to increase the speed of writing / reading and carry the functionality of the basic types (RAID-50, RAID-60, etc.).
If you have noticed some problems, then this is a reason to contact a specialist as soon as possible and check your Raid. It is very important to identify the problem as soon as possible and start taking measures to resolve it. So you can save yourself from data loss. An excellent option would be to ask professionals who can find faults and fix it. There are also some situations when you will have to find someone who can do raid data recovery for you. It’s very important step and not so many people can handle it. So you have to choose some specialists carefully to make sure that you found some really good ones.