In this article I describe how we created a redundant PostgreSQL database on the Amazon cloud using EBSÂ 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.
OpenX Source is a free, open-source ad server that allows publishers to manage their ad inventory and set up complex campaigns with sophisticated targeting rules.
Unfortunately, since OpenX has been focusing on their SaaS solution, the open source version is not well supported anymore. Nevertheless, many publishers still use and maintain their OpenX installations as there is a lack of open source alternatives offering the same flexibility and functionality.
Existing documentation to a great extent assumes a single server installation. For high traffic web sites delivering a large volume of advertisement impressions, there is a need for a more scalable setup.
In this article we will describe the steps we have taken to implement OpenX on a multi-server, auto-scaling setup running in AWS cloud and managed via Scalr. A similar approach could, of course, be configured outside the Scalr or even AWS context. We will mention some of the alternatives.
Cloud HA by Harish Ganesan, CTO at 8KMiles Cloud Solutions
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.
The Service Level Agreement (SLA) discussion puts penalties and compensations on the table. Can we say that the compensation method the customer expects is the same as the Software as a Service (SaaS) vendorâ€™s SLA provides?Â