What is Cluster ? Abhishek Kumar Singh Uzanto Consulting India Pvt. Ltd. Web 2.O Company [email_address]

Types Of cluster Loadbalancing HighAvailability HPC GridComputing

DNS RR Loadbalancing www.example.com . IN A 192.168.1.1 www.example.com . IN A 192.168.1.1 www.example.com . IN A 192.168.1.1 Disadvantages Caching Issues Downed Web Server

DNS RR Loadbalancing www.example.com . IN A 192.168.1.1 www.example.com . IN A 192.168.1.1 www.example.com . IN A 192.168.1.1

OpenSource Loadbalancing Packages pen pound haproxy Ultramonkey LVS OpenSSI(Single System Image)‏

Proxy & Web Server's Loadbalncing Apache- mod_proxy, mod_proxy_balancer RewriteEngine On RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f RewriteRule ^/(.*)$ balancer://mongrel_cluster%{REQUEST_URI} [P,QSA,L] <Proxy balancer://mongrel_cluster> BalancerMember http://127.0.0.1:8000 BalancerMember http://127.0.0.1:8001 BalancerMember http://127.0.0.1:8002 </Proxy>

Nginx------- http { .................. .................. upstream mongrel { server 127.0.0.1:6001 max_fails=1 fail_timeout=60s; server 127.0.0.1:6002 max_fails=1 fail_timeout=60s; server 127.0.0.1:6003 max_fails=1 fail_timeout=60s; } proxy_next_upstream error timeout http_500 http_503; }

server { .................. .................. .................. if (!-f $request_filename) { proxy_pass http://mongrel; break; } .................. .................. }

LVS(Linux Virtual Server)‏ OpenSource Project TCP/IP level loadbalancing Sheduling Algorithms:- 1) Static i- RR ii- WRR

2) Dynamic i- LC overload=(AC*256+IC)‏ ii- WLC priority= overload/weight LVS Types LVS NAT performance issue for high volume traffic LVS DR ARP issue but performance is good LVS TUN Note: LVS Routers Uses GARP to update real servers ARP table .

HighAvailability:- Hearbeat Hearbeat Config 1) Heartbeat Configuration /etc/ha.d/ha.cf 2) Resource Configuration /etc/ha.d/haresources 3) Authentication Configuration /etc/ha.d/authkeys (sha1,md5)‏

Heartbeat Communication Messages:- 1) Heartbeats (statuc messages) 150 bytes long. 2) Cluster Transition Messages i- ip-request ii- ip-request-resp Note: When Primary Server comes online . 3) Retransmission request ( sequence mismatch )‏

Storage Cluster 1) DRBD 2) Heartbeat 3) NFS Distributed Replicaton Of Block Device Network File System

www.linuxvirtualserver.org www.linux-ha.org www.highscalability.com Resources www.slideshare.net/abhishek_singh

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