EC2 Instance Launch Types

- On Demand Instances: short workload, predictable pricing

- Reserved Instances: long workloads (>= 1 year)

- Convertible Reserved Instances: long workloads with flexible instances

- Scheduled Reserved Instances: launch within time window you reserve 

- Spot Instances: short workloads, for cheap, can lose instances

- Dedicated Instances: no other customers will share your hardware

- Dedicated Hosts: book an entire physical server, control instance placement

A) On Demand

- Pay for what you use (biling per second, after the first minute)

- Has the highest cost but no upfront payment 

- No long term commitment

- Recommended for short-term and un-interrupted workloads, where you can't predict how the application will behave

 

B) Reserved Instances

- Up to 75% disconunt compared to On-demand

- Pay upfront for what you use with long term commitment

- Reservation period can be 1 or 3 years

- Reserve a specifit instance type

- Recommended for steady state usage applications (think database)

- Convertible Reserved Instance

 a) can change the EC2 instance types

 b) Up to 54% discount

 - Scheduled Reserved Instances

 a) launch within time window you reserve

 

C) Spot Instances

- Can get a discount of up to 90% compared to On-demand

- You bid a price and get the instance as long as its under the price

- Price varies based on offer and demand

- Spot instances are relaimed with 2 minute notification warning when the spot price goes above you bid

- Used for batch jobs, BIg Data analysis  or worklaods that are resilient to failure

- Not great for critical jobs or databases

 

D) Dedicated Hosts

- Physical dedicated EC2 server for your use

- Full control of EC2 Instance placement

- Visibility into the underlying sockets / Physical cores of the hardware

- Allocated for your account for a 3 year period reservation

- More expensive

- Useful for software that have complicated licensing model (BYOL, Bring Your Own License)

- Or for companies that have strong regulatory or compliance needs

- Instances running on hardware that's dedicated to you

- May share hardware with other instances in same account

- No control over instance placement (can move hardware after Stop / Start)

Q) Which host is right for Hotel?

- On demand: coming and staying in resort whenever we like, we pay the full price

- Reserved: like planning ahead and if we plan to stay for a long time, we may get a good discount

- Spot instances: the hotel allow people to bid for the empty rooms and the highest bidder keeps the rooms
- Dedicated Hosts: book an entire building of the resort

 

EC2 Instance Types - Main ones

 

-R: applications that needs a lot of RAM - in-memory caches

-C: applications that needs good CPU - compute / databases

-M: applications that are balanced (think "medium") - general / web app

- I: applications that need gool local I/O (Instance storage) - databases

- G: applications that need a GPU - video rendering / machine learning

- T2/ T3: burstable instances (up to a capacity)

- T2/ T3 - unlimited : unlimited burst

 

Burstable Instances (T2/ T3)

- AWS has the concept of burstable instances (T2/T3 machines)

- Burst means that overall, the instance has OK CPU performance

- When the machine needs to process something unexpected (a spike in load for example), it can burst, and CPU can be VERY good.

- If the machine bursts, it utilizes "burst credits"

- If all the credits are gone, the CPU becomes BAD

- If the machine stops bursting, credits are accumulated over time

- Burstable instances can be amazing to handle unexpected traffic and getting the insurance that it will be handles correctly

- If your instance consistently runs low on credit, you need to move to a different kind of non-burstable instance

T2/T3 Unlimited

Nov 2017: It is possible to have an "unlimited burst credit balance"

You pay extra money if you go over your credit balance, but you don't lose in performance

Overall, It is a new offering, so be careful, costs could go high if you're not monitoring the health of you instances