Appendix A: Understanding RAID ● 49
When selecting a RAID level for your system, consider the following factors.
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RAID | Data | Capacity | Read | Write | Min Number | Max Number | |
Level | Redundancy | Utilization | Performance | Performance | Spare Drive | of Drives | of Drives |
0 | No | 100% | Superior | Superior | No | 1 | 4 |
1 | Yes | 50% | Very high | Very high | No | 2 | 2 |
10 | Yes | 50% | Very high | Very high | No | 4 | 4 |
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Physical drive utilization, read performance, and write performance depend on the number of drives in the array. Generally, the more drives in the array, the better the performance.
RAID 0 (Non-RAID Arrays)
An array with RAID 0 includes two or more disk drives (maximum twelve) and provides data striping, where data is distributed evenly across the disk drives in
RAID 0 arrays do not maintain redundant data, so they offer no data protection. However, compared to an
Drive segment size is limited to the size of the smallest disk drive in the array. For instance, an array with two 250 GB disk drives and two 400 GB disk drives can create a RAID 0 drive segment of 250 GB, for a total of 1000 GB for the volume, as shown in the following figure.
Disk Drive 1 | Drive Segment Size (Smallest Disk Drive) | ||||
| 250 GB |
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Disk Drive 2 |
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| 250 GB |
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| Disk Drive 1 | 1 | 5 ... | 997 |
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Disk Drive 3 |
| Disk Drive 2 | 2 |
| 998 |
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| 6 ... | |||
400 GB |
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| Disk Drive 3 | 3 | 7 ... | 999 |
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| Not Used | Unused Space: 150 GB |
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Disk Drive 4 | 400 GB | Disk Drive 4 | 4 | 8 ... 1000 | |
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| Unused Space: 150 GB | ||
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| Not Used | |
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Disk Drives in Logical Drive | RAID 0 Logical Drive = 1000 GB | ||||