written 5.2 years ago by
swatisharma
• 1.3k

•
modified 5.2 years ago

Given : Application requires 1TB of storage capacity and performs 4900 IOPS
Solution :
To calculate the time required to perform one I/O = seek time + (Rotational latency) + Transfer time.
Therefore
$5ms + \frac{30000}{15000} + \frac{4KB}{40 MB/s} = 7.1 ms$
Calculate the maximum number of IOPS a disk can perform as $\frac{1}{7.1 ms} = 0.140 \times 10^3 = 140 IOPS$
For acceptable response time, disk controller utilization must be less than 70% Therefore,
we get 140 x 0.7 = 98 IOPS
To meet the application performance requirement we need, 4900/98 = 50 disk
For capacity requirement, we need 1TB/73 GB
i.e. 14 disks.