Load Balancer Comparison: a quantitative approach. a call for researchers ;)

Transcription

1 Load Balancer Comparison: a quantitative approach a call for researchers ;)

2 Complex Internet infrastructure high performance systems clusters grids high availability systems resilient storage resilient services These systems are the building blocks of the awesome Cloud Computing world.

3 Cloud Computing To achieve high performance and high availability and offer cloud computing services we need to: 1. exploit the "power" and the "redundancy" of a bunch of several "small" servers; 2. hide the actual servers from the users; 3. provide a simple interface (such as a web page) to the users. Load balancers are the borders of the clouds. They fulfill the above requirements.

4 Cloud Computing: inside the cloud Can you find the load balancers?

5 Load Balancers: how do they work? Load balancing is a computer networking methodology to distribute workload across multiple computers or a computer cluster, network links, central processing units, disk drives, or other resources, to achieve optimal resource utilization, maximize throughput, minimize response time, and avoid overload. Using multiple components with load balancing, instead of a single component, may increase reliability through redundancy.

6 Cloud Computing: web servers As a matter of fact almost each cloud needs a cluster of web servers to offer its services: web servers web interfaces to complex systems web services implementing APIs... Dozens of different load balancers are employed to give high availability and high performance to these kind of services. Which is the best one?

7 Web servers: how do they work? layer protocol TCP/IP ISO/OSI - HTML HTTP application application 6 presentation 5 session 4 TCP host-to-host transport 3 IP internet network 2 data link 1 physical

8 Load Balancers: flavors layer protocol TCP/IP ISO/OSI Balancers - HTML HTTP application application reverse proxies 6 presentation 5 session 4 TCP host-to-host transport ipvs (linux) 3 IP internet network pf (openbsd) 2 data link 1 physical

9 Load Balancers: flavors Usually load balancers operating at layer 3 and 4 are embedded in the kernel. They offer better performances in terms of latency, cpu load, RAM consumption but they lack functionalities due to the limited awareness of the higher layer protocols. Layer 3 pf: the OpenBSD firewall Layer 4 ipvs: a linux (kernel) load balancer crossaroads: operating in userland pen: operating in userland

10 Load Balancers: flavors Almost all the load balancers operating at layer 7 work in userland as reverse proxy. Project apache nginix KTCPVS notes Just as touchstone nginx [engine x] is an HTTP and reverse proxy server, as well as a mail proxy server, written by Igor Sysoev KTCPVS stands for Kernel TCP Virtual Server. It implements application-level load balancing inside the Linux kernel, so called Layer-7 switching. Since the overhead of layer-7 switching in user-space is very high, it is good to implement it inside the kernel in order to avoid the overhead of context switching and memory copying between user-space and kernel-space. haproxy lighthttp pound The Reliable, High Performance TCP/HTTP Load Balancer Security, speed, compliance, and flexibility -- all of these describe lighttpd which is rapidly redefining efficiency of a webserver The Pound program is a reverse proxy, load balancer and HTTPS front-end for Web server(s) loadbalance Balance is our (still) suprisingly successful load balancing solution being a simple but powerful generic tcp proxy with round robin load balancing and failover mechanisms.

11 Preliminary to-do list stateful vs stateless transaction size... Define meaningful metrics for different use cases: latency throughput RAM consumption CPU load...

12 Preliminary to-do list Define testbed virtual machines (VirtualBox / KVM) real machines (3?) with multiple NICs (8?) switch cables :) Define roles Define experiments

13 Requirements Python Bash GNU/Linux OpenBSD about 100 euros