Why we use cold HDD ?

To store data in cost effective.

what is mean by provisioned IOPS and why it is better then general purpose ?

Provisioned IOPS refers to a specific type of Elastic Block Store (EBS) volume designed to deliver high level of IOPS and allows to explicitly specify the exact number of IOPS that we need for our workload. It is better than General purpose because it offers Better performance, Low level Latency and High Durability.

Types of SDD hard disk ?

1. General Purpose &
2. Provisioned IOPS.

Difference between IOPS and Throughput Optimize ?

IOPS is calculated in numbers,
Throughput is calculated in MBps.

what is a use of IOPS?

Comparing Storage Devices, Sizing for Applications, Troubleshooting and Optimizing Cloud Storage.