先决条件 – RAID , RAID 级别
1. RAID 1：
RAID 1 也称为数据镜像配置，因为它将数据从驱动器 1 复制到驱动器 2。在 RAID 1 中，其中一个驱动器用于存储数据，另一个用作已存储数据的镜像。此级别的 RAID 可在发生任何故障时提供 100% 的数据冗余。
优势 –
它具有良好的容错能力，即即使一个磁盘出现故障也能保持功能。
坏处 –
它很昂贵，因为镜像需要额外的驱动器。
2. RAID 5：
在 RAID 5 中，数据均分在所有磁盘中，最少需要 3 个物理磁盘。 RAID 5 相对于 RAID 1 的主要优点是不需要大的空间，支持恢复时的数据访问和数据的高安全性. RAID 5 通常适用于中等级别的应用程序。
优势 –
引入 RAID 5 是为了使随机写入性能更好。
坏处 –
RAID 5 最多允许恢复 1 个磁盘故障(由于奇偶校验的工作方式)。如果多个磁盘出现故障，则无法恢复数据。
RAID 1 和 RAID 5 的区别：
| S.No. | RAID 1 | RAID 5 |
|---|---|---|
| 1. | RAID 1 stands for Redundant Array of Independent Disk level 1. | RAID 5 stands for Redundant Array of Independent Disk level 5. |
| 2. | In RAID 1, data is not split in the disks. | In RAID 5, data is equally divided in all disks. |
| 3. | The write speed of RAID 1 is slower than RAID 5. | The write speed of RAID 5 is better than RAID 1. |
| 4. | In RAID 1, minimum number of physical disks needed is 2. | In RAID 5, minimum number of physical disks needed is 3. |
| 5. | RAID 1 supports mirroring and redundancy. | RAID 5 does not support mirroring and redundancy. |
| 6. | Data accessing rate is low in RAID 1. | Data accessing rate is high in RAID 5. |
| 7. | In RAID 1, large space is needed for mirror spacing. | In RAID 5, large space is not needed. |
| 8. | In RAID 1, we cannot access data at the time of recovery. | In RAID 5, data can be accessed while recovering data from failure. |
| 9. | Security of data is low in RAID 1. | Security of data is very high in RAID 5. |
| 10. | RAID 1 is best suited for high-end level of applications. | RAID 5 is generally suited for medium level of applications. |