How to check the minimum number of disk drives needed to meet the application’s performance

Hi all,

1) I am stuck with a query related to disk drives. The below question is from one of the EMC links/ external certification material and need the calculations or logic please.:

An organization plans to deploy a new application in their environment. The new application requires 3 TB of storage space. During peak workloads, the application is expected to generate 2450 IOPS with a typical I/O size of 2 KB. The capacity of each available disk drive is 500 GB. The maximum number of IOPS a drive can perform at with 70 percent utilization is 90 IOPS. What is the minimum number of disk drives needed to meet the application’s capacity and performance requirements given a RAID 0 configuration?

The Answer: 28

2) Similarly another scenario:

An organization plans to deploy a new application in their environment. The new application requires 4 TB of storage space. During peak workloads, the application is expected to generate 4900 IOPS with a typical I/O size of 8 KB. The capacity of each available disk drive is 500 GB. The maximum number of IOPS a drive can perform at with a 70 percent utilization is 110 IOPS. What is the minimum number of disk drives needed to meet the application’s capacity and performance requirements given a RAID 0 configuration?

The Answer: 45