To increase the performance and reliability of a server's disk subsystem, we can improve certain components. An effective approach is to extend hard drive functionality with RAID arrays. These are chains of hard drives performing operations simultaneously, delivering higher performance while presenting themselves to the operating system as a single unified system.
Depending on the goals, there are combinations from RAID-0 to RAID-50. In addition, there are several types of RAID controllers: hardware (Hard Raid) and software (Soft Raid).
RAID array levels, the most popular types
There are several RAID array levels, each suited to different situations. Levels 0, 1 and 10 are the most widespread; besides them there are 5 and 50. While RAID 0 boosts performance at the risk of data loss, RAID 1 works with large data sets, ensuring complete data safety through mirroring (duplication) technology, though not speed.
- RAID 0 - maximum performance, but no data redundancy. The capacity of all drives is added together. Any number of drives is allowed.
Example: RAID-0 with 4 drives of 2TB SATA3 each yields an 8TB array with maximum performance but no redundancy. If even one drive fails, all the data is lost. - RAID 1 - the most popular option, built from 2 drives. The available capacity is halved.
Example: RAID-1 with 2 drives of 2TB SATA3 each yields a 4TB array with redundancy. 2TB of space is available for storing data; the second 2TB drive is hidden, and all data is automatically mirrored to it. If one of the drives fails, all the data remains on the second drive and is not lost.
Attention! In some rare cases there is a chance that both drives fail at the same time. 1 drive can fail without data loss. - RAID 5 - this type of array is used with an odd number of drives in the server and offers good protection against data loss.
Example: RAID-5 with 3 drives of 2TB SATA3 each yields a 6TB array, but only 4TB is available for writing. 1 drive can fail without data loss. - RAID 10 - one of the most popular options and the most reliable, usually used with an even number of drives.
Example: RAID-10 with 4 drives of 2TB SATA3 each yields an 8TB array, with only half of the space, 4TB, available for writing. 2 drives can fail without data loss. - RAID 50 - the minimum number of drives is 6. Half of the drives (3 pcs.) are combined into a RAID 5, the other half into another RAID 5, and a RAID 0 is built across these two arrays - for greater performance.
Example: RAID-50 with 6 drives of 2TB SATA3 each yields a fast 8TB array. 2 drives can fail without data loss, but only if they are in different halves.
Types of RAID controllers
The very name «RAID controller» tells us the device's main purpose: managing arrays. An array integrated with the operating system is called software RAID. Integration here means the RAID array is organized as an abstraction directly through the CPU, that is, the controller is a software solution capable of striping and mirroring data. But in practice all the calculations are done by the CPU, and the controller merely receives the end result. This free solution is suitable for low-level arrays: RAID 0, RAID 1 and, less often, RAID 5, sometimes RAID 10. More powerful configurations require constant access to the processor's memory, which can negatively affect the computer's overall performance.
The best, though not always free, way to organize drives in a server is a hardware solution. Only a dedicated RAID controller unit can handle the heavy disk-subsystem load that servers face when processing complex data. It connects to the motherboard via a PCI slot and autonomously handles the management of hard drive arrays. Delivering speed and reliable data mirroring, a hardware RAID controller performs its calculations without loading the CPU, thanks to its own dedicated processor.
Trust in hardware controllers grows year after year. Hosting providers turn to them ever more often for reliability and guaranteed high performance.
If you decide to rent a dedicated server from us, the master-server.pro support team will always help you pick the option with the best balance of price and quality, and will recommend a suitable RAID controller.