系统内冗余或重复数据的度量，表明存储和潜在性能问题效率低下。
1 SDR = 0.9 PB
1 PB = 1.111 SDR
例子:
将15 太空司令转换为奇偶校验的冗余：
15 SDR = 13.5 PB
| 太空司令 | 奇偶校验的冗余 |
|---|---|
| 0.01 SDR | 0.009 PB |
| 0.1 SDR | 0.09 PB |
| 1 SDR | 0.9 PB |
| 2 SDR | 1.8 PB |
| 3 SDR | 2.7 PB |
| 5 SDR | 4.5 PB |
| 10 SDR | 9 PB |
| 20 SDR | 18 PB |
| 30 SDR | 27 PB |
| 40 SDR | 36 PB |
| 50 SDR | 45 PB |
| 60 SDR | 54 PB |
| 70 SDR | 63 PB |
| 80 SDR | 72 PB |
| 90 SDR | 81 PB |
| 100 SDR | 90 PB |
| 250 SDR | 225 PB |
| 500 SDR | 450 PB |
| 750 SDR | 675 PB |
| 1000 SDR | 900 PB |
| 10000 SDR | 9,000 PB |
| 100000 SDR | 90,000 PB |
规则