A Novel Adaptive Distributed Load Balancing Strategy for Cluster

1. A Novel Adaptive Distributed Load Balancing Strategy for Cluster CHENG Bin and JIN Hai showersky@hust.edu.cn, hjin@hust.edu.cn Cluster and Grid Computing Lab Huazhong University of Science & Technology(HUST) Wuhan,430074 International Conference for Young Computer Scientists ICYCS’05, Beijing

2. OutLine • Background • Overview of Our Cluster Architecture • Principle of Our Adaptive Load Balancing Strategy • Performance Evaluation • Conclusions

3. Background • Motivations • Cluster has been a popular method to build high performance network server • Load Balancing is the key problem to provide good scalability and high performance • There are the following problems for existing scheduling strategies for cluster.

4. Background • Overview of Scheduling Systems for Cluster • LVS (Zhang Wensong) • NetDispatcher (IBM) • DPR (Distributed Packet Rewrite) • MagicRouter (UC Berkeley) • ONE-IP (Cisco) centralized distributed Odd-Even scheduling

5. Background • The problems for these existing strategies • Be Based on Active TCP Connection Number • Pay little attention to the diversity of requests and real servers • Static • Need a front-end dispatcher • Not fit to heterogeneous cluster with different hardware configurations • Our Scheduling Strategy • Dynamic • Adaptive • Heterogeneous Cluster • Distributed, Without front-end dispatcher server participation

6. Our Cluster Architecture

7. SYN+ACK SYN ACK Load Balancing Strategy • The Principle of Our Scheduling Method Hehe! I Get this connection Request RTSP, HTTP and so on

8. ISN = b matched Load Balancing Strategy • One Case

9. Analysis • The key problems • The real server with least load should response the client at first • The packet from least load should arrive at first. • How to address the problems? • To calculate the load of local server • To make the delay for SYN packet comparable with the delay on network To be so sensitive that the server with the least load can run for the current request easily

10. Load • The method to calculate the load of real servers

11. Delay • Use RTT/2 as the baseline of the delay time of SYN Packet TDhop --- a constant value 100ms. TTLS ---the initial TTL value set by the sender. TTLR ----the TTL value of the SYN packet received by the real server

12. Performance Evaluation • Experimental Environment

13. Experimental Result • Load Balancing the CPU utilization changing procedure in 30 seconds 1) fluctuates between 75% and 95% 2) their mean value keeps close to 85%

14. Experimental Result • Load Balancing Comparison on mean CPU utilization among ADLB, LVS, ONE-IP Get better load balance for heterogeneous cluster

15. Experimental Result • Scalability Throughput of Cluster Web Server provide a nearly linear increase in overall reply rates

16. Experimental Result • Scalability aggregated NET I/O bandwidth of Cluster Web Server with different connection arrival rate and different node number

17. Experimental Result • Response Time increase 30~100 ms

18. Conclusions • Propose a New load balancing Strategy for Cluster • Better for Heterogeneous Cluster • Adaptive • Easy Configuration • Dynamic • From the experimental results, our strategy achieves good scalability and performance. Especially, it is better for heterogeneous cluster than other algorithms

19. Thank you for your patience !