Virtual Clusters: A Cost-Benefit Look Into the Future of Computing at CMU Alok Chatterjee Anusha Krishnakumar November 25 th 2002

Introduction - What is a Virtual Cluster? VC Locations – University Center VC (Apple grant) – GSIA (IBM ThinkPads) “Laptop check-out system” very similar to library system Background on “VC’s” – Planning process begun in 1994

GSIA Virtual Cluster First VC opened in 1998 (pilot program) – 28 IBM ThinkPads GSIA full service VC – 50 ThinkPads today Various known problems going into VC project

GSIA VC Costs Main costs associated with VC: – Need for More Man-Power – Network issues (wireless supports far less bandwidth) Further costs: – Laptop / Battery lifecycle Replacement costs – Skilled labor / Training costs – Waiting time Back-to-back classes, etc – Laptop availability Not available 24 hours

Need for More Man-Power Training (i.e., logistics for running the cluster) Cluster needs to be constantly staffed Certain Technical Skills (e.g., technical support) Higher salaries associated with the above attributes

Network issues Wireless supports far less bandwidth, resulting in more jams Users closer to wireless hubs tend to use up more bandwidth, detracting from other users’ usage capabilities

GSIA VC Benefits Various benefits too – Space conservation – Energy savings – Flexibility / Mobility

Space Conservation Small checkout hub, located near classrooms / auditoriums The GSIA virtual cluster takes up approximately one- tenth of the space that the Baker cluster does Given the shortage of classrooms on campus, the potential benefits resulting from more virtual clusters, and, by extension, fewer desktop clusters, could be enormous

Energy Savings – Laptops tend to take less energy than desktops Dependent upon the power consumption of the battery charger These computers will NOT be left on all the time like the cluster computers

Flexibility / Mobility – All the benefits of a laptop, plus an Ethernet connection – Especially useful given space constraints – Can effectively control the size of the cluster

Wrap-up Various benefits and costs as mentioned earlier – Space, energy, replacement costs, etc Success of Virtual Cluster system today – Laptops checked out on a regular basis, popular with students and professors Our recommendation – Expand the virtual cluster service and eliminate some desktop clusters

Questions?