首先需要知道I/O中读操作(Read)与写操作(Write)所占的百分比。然后通过下列公式，将主机的IOPS需求转换成硬盘实际IOPS负载：
| RAID类型 | 公式 |
| RAID 5和3 | Drive IOPS = Read IOPS + 4*Write IOPS |
| RAID 6 | Drive IOPS = Read IOPS + 6*Write IOPS |
| RAID 1和1/0 | Drive IOPS = Read IOPS + 2*Write IOPS |
假定4500 IOPS中读/写比是2:1，则不同RAID类型Drive IOPS要求分别如下：
RAID 1/0: (2/3)*4500 + 2*(1/3)*4500 = 6000 IOPS
RAID 5: (2/3)*4500 + 4*(1/3)*4500 = 9000 IOPS
RAID 6: (2/3)*4500 + 6*(1/3)*4500 = 12000 IOPS
再参照下表中不同类型硬盘单块IOPS参数，得出需要多少块硬盘：
Throughput MB/s = IOPS * KB per IO / 1024
| 硬盘类型 | IOPS |
| Fibre Channel 15k rpm | 180 |
| SAS 15k rpm | 180 |
| Fibre Channel 10k rpm | 140 |
| SATA 7.2k rpm | 80 |
| SATA 5.4k rpm | 40 |
| Flash drive | 2500 |
假定选用FC 15K RPM硬盘，则：
RAID 1/0: 6000/180 = 34 块
RAID 5: 9000/180 = 50 块
RAID 6: 12000/180 = 67 块
注：实际情况下还需考虑Vault Drivers (共5块)以及Hot Spares (建议每30块硬盘一个)。
最后，如果选用600GB FC硬盘来实现20TB可用空间，则RAID 1/0需要78块，RAID 5需要42块，具体计算方法参考：
原英文讨论链接：
原英文讨论链接：
https://community.emc.com/message/414474
https://community.emc.com/message/556556
https://community.emc.com/thread/117796
https://community.emc.com/thread/91112
| 应用类型 | IO大小 | 读写比例 | 随机与顺序读写比例 |
| Web File Server | 4KB、8KB、64KB | 95%读/5%写 | 75%随机/25%顺序 |
| Web Server Log | 8KB | 100% Write | 100%顺序 |
| OS Paging | 64KB | 90%读/10%写 | 100%顺序 |
| Exchange Server | 4KB | 67%读/33%写 | 100%随机 |
| Workstation | 8KB | 80%读/20%写 | 80%随机/20%顺序 |
| Media Streaming | 64KB | 98%读/2%写 | 100%顺序 |
| OLTP - Data | 8KB | 70%读/30%写 | 100%随机 |
| OLTP - Log | 512bytes - 64KB | 100%写 | 100%顺序 |