KnowYourCloud Community

Case Study: PostgreSQL DB Replication Between AWS Regions

In this article I describe how we created a redundant PostgreSQL database on the Amazon cloud using EBS snapshots as backups to deploy a PostgreSQL DB server DR mobile application for one of our customers.

PostgreSQL 9.1 includes new capabilities for asynchronous fast replication syncing between master and slaves. The master server streams new data to the current available slave. This version includes great improvements that generated significant fast WAL (Write Ahead Log) processing, which generates replication and fast launching capabilities for the slave servers.

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The Art of Infrastructure Elasticity

Enter DynamoDB - 9 Steps Manual

The following presentation describe briefly how to start with DynamoDB to support PHP sessions. Check out the full article – PHP Sessions with a DynamoDB Backend, includes why to move to DynamoDB (AWS Cloud Scalable and Consistently performing NoSql as a service) and additional important considerations.

PHP Sessions with a DynamoDB Backend

The problem

When scaling an application, session sharing across multiple web servers is one of the first issues that need to be tackled. This issue is a bit more complex in autoscaling setups in the cloud where application servers are added or removed from the load balancer as traffic and load increases or decreases.

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Some AWS EBS Benchmarks and Best Practices by Greplin:tech

Greplin built a lot of their infrastructure on Amazon’s Elastic Compute Cloud (EC2) and Elastic Block Store (EBS). Following the serious AWS 2011 April outage they tested in deep the EBS performance and came with benchmarks with regards to disk I/O.  We invite you to check it out.

The great informative post includes best practices, benefits and Caveats. The post led to some great comments also in this YCombinator thread  with some more referrals to additional relevant knowledge resources.

Architecture Blueprints for achieving High Availability in AWS

Cloud HA by Harish Ganesan, CTO at 8KMiles Cloud Solutions

Introduction to Amazon DynamoDB

Servers are not Balanced across Multiple Availability Zones

AWS Elastic Load Balancing (ELB) automatically distributes incoming traffic to your application to multiple EC2 instances that are attached to your Elastic Load Balancer. At any time, Elastic Load Balancing detects the unhealthy instances in the pool, and distributes the incoming traffic only to the healthy instances until the unhealthy ones are restored.

In order to achieve greater fault tolerance and thus higher availability, it is recommended to distribute your instances in different geographical zones so that if all the instances in a single datacenter are not healthy, as may occur when there is an outage, your application will run in a datacenter in a different zone.

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