What is RAID
RAID (redundant array of independent disks) is way of storing same data in different places on multiple hard disks to protect all the content in case of a drive failure, it must be added that not all RAID levels provide redundancy.
How RAID works
RAID works like a storage virtualisation technology that combines several physical disk drives into one or more logical volumes for the purpose of data redundancy, performance improvement or for both reasons at the same time.
Data is distributed across all drives in different ways depends on RAID level we set the array in. The levels of RAID are always followed by number, for example RAID 0, RAID 1, RAID 5, RAID 6 etc. Each scenario provides a difference balance between reliability, availability of storage, performance and of course capacity.
What are the levels of RAID:
RAID 0 is the only level of RAID which does not provide any kind of protection against the drive failures, it is purely there for speed and to have one big volume available, in scenario where we have 10TB drives in 8-bay enclosure set as RAID 0 we will get 80TB of accessible storage.
RAID 1, also called a mirror, in that option our data is identically stored into two drives were only one drive is visible to us and a second one is hidden for the backup purpose. This option is valid only for arrays with 2-bays, you can of course set multiple RAIDs on bigger enclosures like have 2x RAID 1s in 4-bay. That version of RAID is good enough for basic and small units, it does work great where we do not have much data to be kept safely
RAID 5, here the parity information is distributed among all drives, we have single redundancy in that scenario, if one drive decide to die, our data will be still safe, like in RAID 1, one drive will be hidden for that backup purpose and we see the total storage of combined numbers of bays minus the bay allocated for that backup. We can start RAID 5 even with 3 drives.
RAID 6, this is more advanced RAID setup and more popular on enclosures with 8+ bays. It has double redundancy mode which means that two drives are hidden for backup purpose, you can set the RAID 6 on any systems with at least 4-drives. The total storage will be the combined numbers of bays minus two allocated for that backup.
RAID 10, this is basically a RAID 0 array of mirrors, you need drives to be in pairs to work with that system. For example you can have 4-bay set as RAID 10 where you will only see capacity of two drives (like in RAID 6) but the speed will be much better thanks to the RAID 0 part.
JBOD, it’s just a bunch of disks, usually not RAIDed, they are accessible individually and come up as individual drives.
These are the most common RAID settings.
Which RAID is right for me?
There is no general answer for this question, otherwise there would not be so many options available. Everyone is different and everyone have got divergent needs so the right solution for you need to be made only for you. Depends if you need speed, security or maybe balance between two.
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