EC2 Flashcards
Elastic Cloud Computer intro
Web-service that provides resizable compute capacity in the cloud.
Reduces time required to obtain and boot new server instances to minutes allowing to quickly scale up and down as computer requirements change.
Pricing Models
On-demand Savings plan Reserved instances Spot Dedicated Host
Model - On-demand
1) On demand (pay fixed rate by hour/second)
○ Low cost and flexibility without upfront pay and long-term commitment
○ Apps with short term, unpredictable workloads that can’t be interrupted
○ Apps being dev/tested for first time
Model - Reserved
Steady/predictable usage
Required reserved capacity
Up-front payments to reduce total computing costs even further
Reserved Instances provide you with a significant discount (up to 75%) compared to On-Demand instance pricing. In addition, when Reserved Instances are assigned to a specific Availability Zone, they provide a capacity reservation, giving you additional confidence in your ability to launch instances when you need them.
Standard RIs: These provide the most significant discount (up to 72% off On-Demand) and are best suited for steady-state usage.
Convertible RIs: These provide a discount (up to 54% off On-Demand) and the capability to change the attributes of the RI as long as the exchange results in the creation of Reserved Instances of equal or greater value. Like Standard RIs, Convertible RIs are best suited for steady-state usage.
Scheduled RIs: These are available to launch within the time windows you reserve. This option allows you to match your capacity reservation to a predictable recurring schedule that only requires a fraction of a day, a week, or a month.
Model - Reserved - Standard
Best suited for steady-state usage. Up to 75% off on demand instances More you pay up front or longer the contract the greater the discount Cannot change between instance types Cannot change region.
Model - Reserved - Convertible
These provide a discount (up to 54% off On-Demand) and the capability to change the attributes of the RI as long as the exchange results in the creation of Reserved Instances of equal or greater value. Like Standard RIs, Convertible RIs are best suited for steady-state usage.
Can change instance types, OS etc.
Model - Reserved - Schedulded
§ If you have a launch window (school times) where people will log in.
§ Schedule having reserved instances to specific time window
Model - Spot
○ Apps that have flexible start/end times
○ Apps only feasible at very low compute prices
○ Urgent computing needs with large capacity
○ Charged for the hour (but rounded up if AWS terminates). Save 90% compared to on demand.
○ Can use for:
§ Stateless, fault tolerant, flexible apps like Big Data, containerized workloads, CI/CD, web-servers, HPC, other test/dev work.
§ Not for critical applications, persistent workloads, databases.
○ How to use:
§ Decide on max spot price. New instance will be provisioned if below spot price
§ Hourly spot price depends on region and capacity. Varies like stock market.
§ If spot price is over your max spot price you have 2 minutes to terminate instance.
□ Can stop using spot block. If price goes over yours you have 1-6.
§ Can see pricing history of spot instances (around 3-5 cents)
Model - Spot - Fleets
collection of spot instances and on-demand instances
§ Attempts to launch spot instances to meet your hardware requirements but if it’s not met because price too high it will do the rest using on-demand.
§ Will maintain target capacity by relaunching spot.
§ Setup different launch pools defining: EC2, OS, AZ
§ Have multiple pools and fleet will choose best implementation
§ Will stop launching instances once you reach price threshold or capacity desire
§ Strategies:
□ capacityOptimized - spot instances come from pool with optimal capacity for no. of instances launches
□ lowestPrice - spot instances from pool with lowest price (default)
® InstancePoolsToUseCount - spot distributed across spot instance pools you specific. Only in combination with lowest price
□ Diversified - spot instances distributed across all pols
Model - Dedicated
Dedicated hosts (physical server dedicated for your use)
○ Useful for regulatory requirements
○ Great for licensing
○ Can purchase dedicated hosts on-demand. Or reservation for 70% off
Elastic Block Storage (EBS)
• Persistent block storage volumes to use with EC2 instances. Each EBS volume replicated within AZ to protect from component failure offering high availability and durability. • EBS Storage types ○ General purpose (SSD) § Balance price and performance § Use case: Most workloads § API Name: gp2 § Size: 1GiB - 16TiB § Max IOPS/Volume: 16K/volume ○ Provisioned IPS (SSD but faster) § Highest performance SSD for mission-critical apps § Use case: Databases § API Name: io1 § Size: 4GiB - 16TiB § Max IOPS/Volume: 64K ○ Throughput Optimized HDD § Cheap HDD for frequently accessed throughput to intensive workloads § Use case: Big Data & Data warehouses § API Name: st1 § Size: 500 GiB - 16TiB § Max IOPS/Volume: 500 ○ Cold HDD § Cheapest SSD for less frequently accessed workloads § Use case: File servers § API Name: sc1 § Size:500GiB - 16TiB § Max IOPS/Volume: 250 ○ Magnetic (HDD) § Previous gen HDD § Use case: Infrequent data access (if you don't use Glacier Archive for some reason) § API Name: Standard § Size: 1GiB - 1TiB § Max IOPS/Volume: 40-200
EBS General Info
EBS in same AZ as EC2, but can move instances.
If you turn off EC2 then EBS volume shuts down.
Can add more storage to EC2.
Can change volume type of EC2.
Can’t delete snapshot of rood device of an EBS volume.
Terminating EC2 means root volume gone but additional volume persist.
AMI Types
Can select based on:
• Region
• OS
• Architecture 32/64BIT)
• Launch permissions
• Storage for the root device
○ Instance store (ephemeral storage)
§ Root device for an instance launched from AMI is using instance store volume created from template from S3
§ Can’t stop this volume or you lose all of your data if the underlying host stops
○ EBS
§ Root device for instance launched from AMI is using EBS volume created from Amazon EBS snapshot
§ Can be stopped.
○ By default both root volumes deleted on termination but EBS you can tell AWS to keep root device volumes
Elastic File System EFS
Elastic File System.
• File storage for EC2 instances.
• Easy to use with simple interface to create/configure file systems quickly.
• Elastic storage capacity and can shrink/grow auto as you add/remove files.
• One EC2 can be shared by 2 EFS (unlike EBS).
• Supports NFSv4
• Only pay for storage used (no pre-provisioning required like in EBS).
• Can scale up-to PB
• Can support thousands of concurrent NFS in multiple AZ’s within a region
• Read after write consistency
• First network file sharing protocol native to Unix/Linux
Region based therefor need to choose which AZ to spread across.
