What is Amazon Elastic Block Store (EBS)?

Amazon Elastic Block Store (EBS) high-performance block storage service designed to be used with EC2 for both throughput and IOPS at any scale.

We can mount volumes as devices on EC2 instances. We can mount multiple EBS volumes to one EC2 instance but you can’t mount one EBS Volume to multiple EC2 instances.

EBS are of 5 types:

1. General Purpose SSD (gp2) : 
   We can use EBS General Purpose SSD (gp2) if IOPS is important and IOPS < 80000 but IOPS > 16000 is required and latency > 1ms is okay and the cost is important. This EBS Volume is suitable in most cases.
   Use Case: 
   System boot volumes
2. Provisioned IOPS SSD (io1) : 
   We can use EBS provisioned IOPS (io1) if IOPS is important and IOPS < 80000 but IOPS > 16000 is required and latency > 1ms is okay and also performance is more important than cost. 
   Use Case: 
   Large database workloads (MongoDB)
   MySQL 
   SAP 
   Oracle
   Postgres
3. Throughput Optimized HDD (st1): We can use this when throughput is important than IOPS. This can’t be a boot volume. Mostly used for streaming workloads requiring consistent, fast throughput. 
   Use Case: 
   Big data
   Data warehouses
   Log processing
4. Cold HDD (sc1): We can use this when throughput is important than IOPS but we can’t use this as a boot volume and is used for large volumes of data that is infrequently accessed. It is for the lowest storage cost.
   Use Case:
   Throughput-oriented storage for large volumes of data that is infrequently accessed
5. Magnetic Volume — It is the previous generation HDD and used for workloads where data is infrequently accessed.