# IOPS:

• Input Output Operations Per Second.
• An important metric that measures the performance of cloud storage.
• How swiftly read and write data can be executed from a hard drive.
• Learn more .

# Elasticity:

The ability to acquire resources as you need them and release resources when you no longer need them. E.g. auto-scaling.

# Scalability:

Being able to accommodate a large load by scaling up or out.

# Agility:

New IT resources are available on-demand.

# Distributed systems:

Multiple computers work together to solve a common problem (ref).

Computer systems whose inter-communicating components are located on different networked computers (ref).

# Manged service:

Cloud computing services provided by AWS.

They handle the underlying infrastructure and operational tasks, allowing users to focus on their applications and workloads. E.g. S3, RDS.

# RDBMS

Relational Database Management System.

# ACL:

Stands for Access Control List.

It is a list of rules that specifies which users or systems are granted or denied access to a particular object or system resource.

# Auto Scaling Group

To scale we have 2 options:

	Vertical Scaling	Horizontal Scaling
How it works	Increase the size (e.g. t2.micro => t2.large).	Increase the number of instances (e.g. more ElastiCache instances).
Considerations	Limited (Cannot be scaled indefinitely).	Distributed systems: more work regarding data integrity and other aspects of a distributed system. High-availability: aligned with Elasticity. You can setup your ASG template to provision new EC2 instances in different AZs.
AKA	Scale up/down.	Scale out/in.

# Availability

$\frac{\mathrm{Uptime}}{\mathrm{Uptime}+\mathrm{Downtime}}$

The percentage of the expected time that a service is actually operational & accessible.

# Latency

The necessary time for a packet on network to reach the other party (e.g. a server).