1. CloudWatch’s Free Tier metric update frequency is 5 minutes
  2. In the Detailed monitoring data available for your EBS volumes, provisioned IOPS volumes automatically send 1 minute metrics to CloudWatch.



  1. ec2-revoke RevokeSecurityGroupIngress means remove one or more rules from a security group. The value you specify in the revoke request must be existing rule’s value for the rule to be removed.
  2. ec2-create-group CreateSecurityGroup means create a security group for use with your account.

NOTE: user have a limit on the number of security group one can create. 3. To go to EBS in EC2 console, click Volumes in EC2 console. 4. All EC2 instances are assigned two IP addresses at launch, you can use Private IPv4 addresses for communication between instances in the same network (EC2-Classic or VPC) 5. To view all categories of instance metadata from within a running instance, use the URL


  1. To change security group membership for interfaces owned by other services, use the console or command line interface for that service


EMR File System, or EMRFS is

  • An implementation of HDFS on AWS which allows clusters to store data on S3
  • Uses data directly on S3 without ingesting into HDFS
  • Reliability, durability and scalability of S3
  • Resize and terminate EMR clusters without losing data
  • Can support multiple EMR clusters point to the same S3 buckets

Consistent View

  • Checks for list and read-after-write consistency for new S3 objects written or synched with EMRFS
  • Retry logic if inconsistency is detected
  • Metadata in DynamoDB keeps track of S3 objects


  1. An IAM group is a collection of users. You can use groups to specify permissions for a collection of users, which can make those permissions easier to manage for those users.



  1. While launching an RDS DB instance, on DB Instance Detail page one can select the Available Zone.
  2. When you provision a Multi-AZ DB instance, RDS automatically creates a primary db instance and synchronously replicates the data to a standby db instance in a different Availability Zone.




  1. S3 stands for Simple Storage Service
  2. Reduced Redundancy option in S3 is less redundancy for a lower cost

Region vs Availability Zone

Amazon EC2 is hosted in multiple locations world-wide. These locations are composed of Regions and Availability Zones.

  • Each Region is a separate geographic area.
  • Each Availability Zone is a isolated locations under Region.

Each Region is completely independent. Each Availability Zone is isolated, but the Availability Zones in a region are connected through low-latency links.

AWS Region and Availability Zones

Redshift vs RDS

AWS RDS offers an RDBMS used to answer MANY SMALL FAST queries. Primarily used by END CUSTOMERS. This is also known as an OLTP(Online Transaction Processing) system.

AWS Redshift is a Data Warehouse, used to anser A FEW, LONG RUNNING queries on LARGE sets of data. Primarily used by INTERNAL users. This is also known as an OLAP(Online Analytics Processing) system.