Asymmetric Active-Active High Availability for High-end Computing

Linux clusters have become very popular for scientific computing at research institutions world-wide, because they can be easily deployed at a fairly low cost. However, the most pressing issues of today‘s cluster solutions are availability and serviceability. The conventional Beowulf cluster architecture has a single head node connected to a group of compute nodes. This head node is a typical single point of failure and control, which severely limits availability and serviceability by effectively cutting off healthy compute nodes from the outside world upon overload or failure. In this paper, we describe a paradigm that addresses this issue using asymmetric active-active high availability. Our framework comprises of n + 1 head nodes, where n head nodes are active in the sense that they provide services to simultaneously incoming user requests. One standby server monitors all active servers and performs a fail-over in case of a detected outage. We present a prototype implementation based on a 2 + 1 solution and discuss initial results.