问题
can i add aerospike cluster under aws autoscale? Like . my initial autoscale group size will 3, if more traffic comes in and if cpu utilization is greater then 80% then it will add another instance into the cluster. do you think it is possible? and does it has any disadvantage or will create any problem in cluster?
回答1:
There's an Amazon CloudFormation script at aerospike/aws-cloudformation that gives an example of how to launch such a cluster.
However, the point of autoscale is to grow shared-nothing worker nodes, such as webapps. These nodes typically don't have any shared data on them, you simply launch a new one and it's ready to work.
The point of adding a node to a distributed database like Aerospike is to have more data capacity, and to even out the data across more nodes, which gives you an increased ability to handle operations (reads, writes, etc). Autoscaling Aerospike would probably not work as you expect it. This is because of the fact that when a node is added to the cluster a new (larger) cluster is formed, and the data is automatically balanced. Part of balancing is migrating partitions of data between nodes, and it ends when the number of partitions across each node is even once again (and therefore the data is evenly spread across all the nodes of the cluster). Migrations are heavy, taking up network bandwidth.
This would work if you could time it to happen ahead of the traffic peaking, because then migrations could be completed ahead of time, and your cluster would be ready for the next peak. You would not want to do this as peak traffic is occuring, because it would only make things worse. You also want to make sure that when the cluster contracts there is enough room for the data, enough DRAM for the primary-index, as the per-node usage of both will grow.
One more point of having extra capacity in Aerospike is to allow for rolling upgrades, where one node goes through upgrade at a time without needing to take down the entire cluster. Aerospike is typically used for realtime applications that require no downtime. At a minimum your cluster needs to be able to handle a node going down and have enough capacity to pick up the slack.
Just as a note, you have fine grain configuration control over the rate in which migrations happen, but they run longer if you make the process less aggressive.
来源：https://stackoverflow.com/questions/34759291/add-node-to-existing-aerospike-cluster-using-autoscale