2017-02-07 15:05:37
Because RAID 5 needs to be fault-tolerant and parallel reading, it means that the capacity of one drive letter is reduced (for fault-tolerant backup is used). By the way, RAID 0 reduces the capacity of half of the drive letter.
I was too lazy to hit it myself, so I came here to copy:
The number of available disks for RAID5 is: n-1.
In other words, after the disk is RAID5, the system can use capacity is: single disk capacity* (n-1)
So the available capacity of your 4 disks is: 500G*(4-1)=1500G=1.5T Search
RAID5 stores data and corresponding parity information on each disk that constitutes RAID5, and the parity information and corresponding data are stored on different disks respectively. In any N-1 disk, complete data is stored, that is, there is space equivalent to the capacity of a disk to store parity information. Therefore, when a disk of RAID5 is damaged, the data integrity will not be affected, thus ensuring data security. When the damaged disk is replaced, RAID will automatically use the remaining parity information to reconstruct the data on the disk to maintain the high reliability of RAID5.
RAID5 has nothing to do with hot spare disks, and it is not possible to use hot spare disks. It is more reliable if used. It doesn't matter if you don't need it. It mainly depends on the importance of your data.
https://blog./zhaoshilei/1895662