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CloudWatch CloudWatch’s Free Tier metric update frequency is 5 minutes In the Detailed monitoring data available for your EBS volumes, provisioned IOPS volumes automatically send 1 minute metrics to CloudWatch. EBS EC2 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. ec2-create-group CreateSecurityGroup means create a security group for use with your account....

Book Structure Part one: the core differences between people in the four quadrants Part two: personal change, who you have to be instead of what you have to do Part three: how to find success in the B & I quadrants Income is not from what we learnt from school, rather than than it’s about our values, interests, strengths, and weaknesses. Changing the quadrants requires changing in the core of who you are, how you think, and how you look at the world....

Reference Wenfeng: Why I Declined Offers From SumoLogic, Amazon, Uber and Choose Quantcast

Database Scaling is one of the most important topics in System Design . Normally for any large scale application architecture, the database is usually going to be where your performance bottleneck is. That’s because while most of your application are essentially stateless, so that you can scale them horizontally as much as you need. All the applications will hit the database for retrieving data, or writing new data. Key Information Most of the large-scale web application are very read-intensive, usually around 95% read request and 5% write requests....

Why Caching? Improve performance of application. Save money in long term. Speed and Performance Reading from memory is much faster than disk, 50~200x faster. Can serve the same amount of traffic with fewer resources. With the rapid performance benefits aforementioned, you can server much more many more requests per second with the same resources. Pre-calculate and cache data. This is something Twitter implemented, they occasionally pre-compute what your time-line is, i....