BtrPlace: A Flexible Consolidation Manager for Highly Available Applications

The massive amount of resources found in data centers makes it possible to provide high availability to multitier applications. Virtualizing these applications makes it possible to consolidate them on servers, reducing runtime costs. Nevertheless, replicated VMs have to be carefully placed within the data center to provide high availability and good performance. This requires resolving potentially conflicting application and data center requirements, while scaling up to the size of modern data centers. We present BtrPlace, a flexible consolidation manager that is customized through configuration scripts written by the application and data center administrators. BtrPlace relies on constraint programming and an extensible library of placement constraints. The present library of 14 constraints subsumes and extends the capabilities of existing commercial consolidation managers. Scalability is achieved by splitting the data center into partitions and computing placements in parallel. Overall, BtrPlace repairs a nonviable placement after a major load increase or a maintenance operation for a 5,000 server data center hosting 30,000 VMs and involving thousands of constraints in 3 minutes. Using partitions of 2,500 servers, placement computing is reduced to under 30 seconds.