When I am studying LPIC, I sometimes get questions about RAID, but I want to keep it as a memorandum because my understanding is vague.
RAID is a technology that treats multiple HDDs as if they were one HDD. RAID has several modes, and each mode can increase the capacity, speed, and reliability of the disk.
| RAID type | Explanation |
|---|---|
| RAID0 | A method of distributing and storing data on multiple disks, also called striping. Reading and writing of discs can be speeded up, but if one of the discs breaks, data cannot be read. |
| RAID1 | A method of storing exactly the same data as one disk on another, also known as mirroring. Even if one of the disks is broken, the data will not be lost. |
| RAID5 | The data and the data for consistency check (parity) are distributed. It is highly safe because it speeds up disk reading and allows data to be restored by parity even if one of the disks is broken. However, it may take some time to calculate the consistency check data at the time of writing. Available from 3 disks. |
| RAID6 | Although the technology is the same as RAID5, RAID6 can be used from 4 disks, and compared to RAID5, one more disk can be broken at the same time, so it is more secure. However, the writing speed will be slower accordingly. |
reference https://gihyo.jp/book/2016/978-4-7741-8034-2 https://www.pro.logitec.co.jp/houjin/usernavigation/hddssd/20190809/ https://www.elecom.co.jp/pickup/column/storage_column/00003/
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