Configuration Strategies
The most important factors in RAID array configuration are: drive capacity, drive availability (fault tolerance), and drive performance. You cannot configure a logical drive that optimizes all three factors, but it is easy to choose a logical drive configuration that maximizes one factor at the expense of the other two factors, although needs are seldom that simple.
Maximize Capacity RAID 0 achieves maximum drive capacity, but does not provide data redundancy. Maximum drive capacity for each RAID level is shown below. OEM level firmware that can span up to 4 logical drives is assumed.
| RAID | Description | Drives | Capacity |
|
| Level |
| Required |
|
|
| 0 | Striping | 1 – 32 | (Number of disks) X capacity of |
|
|
| without parity |
| smallest disk |
|
|
|
|
|
|
|
| 1 | Mirroring | 2 | (Capacity of smallest disk) X (1) |
|
|
|
|
|
|
|
| 3 | Striping with | 3 – 32 | (Number of disks) X (capacity of |
|
|
| fixed parity |
| smallest disk) - (capacity of 1 disk) |
|
|
| drive |
|
|
|
| 5 | Striping with | 3 – 32 | (Number of disks) X (capacity of |
|
|
| floating parity |
| smallest disk) - (capacity of 1 disk) |
|
|
| drive |
|
|
|
| 10 | Mirroring and | 4 – 32 (Must | (Number of disks) X (capacity of |
|
|
| Striping | be a multiple | smallest disk) / (2) |
|
|
|
| of 2) |
|
|
| 30 | RAID 3 and | 6 – 32 (Must | (Number of disks) X (capacity of |
|
|
| Striping | be a multiple | smallest disk) – (capacity of 1 disk X |
|
|
|
| of arrays) | number of Arrays) |
|
|
|
|
|
|
|
| 50 | RAID 5 and | 6 – 32 (Must | (Number of disks) X (capacity of |
|
|
| Striping | be a multiple | smallest disk) – (capacity of 1 disk X |
|
|
|
| of arrays) | number of Arrays) |
|
|
|
|
|
|
|
|
|
|
|
|
|
Cont’d
40MegaRAID Enterprise 1600 Hardware Guide