Arrays

A server array is a group of mostly identical EC2 instances where the number of instances varies (i.e., scales) over time in response to changing factors. RightScale offers both alert and queue-based arrays. 

Alert-based server arrays are typically used for auto-scaling a website's application servers.   You can also create a server array schedule where you define new resize parameters over the course of a day/week.  See Server Array Schedule.

Queue-based server arrays are normally used for RightGrid applications where you scale the number of worker instances based on jobs in the queue.  Currently, you can either resize a queue-based server array based on the number of jobs in the queue or the amount of time a job is in the queue.  The elasticity daemon checks queues every 30 seconds to determine if a resize action should be taken on the server array based on the array's elasticity parameters.