High Availability/ Clustering with Zend Platform

Transcription

1 High Availability/ Clustering with Zend Platform David Goulden Product Manager Copyright 2007, Zend Technologies Inc.

2 In this Webcast Introduction to Web application scalability using clusters & Zend platform s session clustering as the solution for scaling Web clusters. Agenda: Web scalability background About sessions About clusters Solutions for synchronizing sessions in clusters Zend s session clustering solution Building the PHP Stack for the Enterprise 11-Jun-08 2

3 The Terms Scalability the ability to provide the same quality of experience to an ever increasing number of users. Performance the ability to provide the same quality of experience to an increasing number of users on a given system. Scalable solution a solution that will support user number growth indefinitely. High Availability (HA)- a solution that uses a scalable infrastructure to provide availability and continuity of mission critical business applications. Building the PHP Stack for the Enterprise 11-Jun-08 3

4 Web application scalability background Copyright 2007, Zend Technologies Inc.

5 The single-server system As load increases Building the PHP Stack for the Enterprise 11-Jun-08 5

6 The Web Cluster Web Servers Building the PHP Stack for the Enterprise 11-Jun-08 6

7 About Sessions Copyright 2007, Zend Technologies Inc.

8 What are user sessions? Browser Session ID HTTP REQUEST Server Session Data HTTP protocol - the heart of the Web communication Browser <-> server communication transfer media such as HTML, XML etc using HTTP protocol. HTTP protocol runs on top of TCP/IP communication While TCP/IP is a connection oriented protocol, HTTP isn t. HTTP is Stateless HTTP memory of a connection ends after each server request <-> response coupling. User session includes multiple HTTP request <-> response interaction. Maintaining user sessions allows the application to keep track of user specific data and logic between requests Typical use of sessions : shopping cart Building the PHP Stack for the Enterprise 11-Jun-08 8

9 Tracking user sessions Keeping a unique key - the common method for tracking user sessions The key is transferred between browser and server with each request The key is used to track requests by a specific client The key points to user-related data Two methods for transporting the key: Custom URL, Cookie Custom URL - An identifying string is added to the URL Cookie a file saved in the browser memory or on the client computer Building the PHP Stack for the Enterprise 11-Jun-08 9

10 Saving user data The key is an index to user data User data is stored on the Web server PHP provides session APIs managing sessions transparently <?php //creates a session or resumes the current one // based on the current session id session_start(); // count requests and save into session example if (!isset($_session['count'])) { $_SESSION['count'] = 0; } else { $_SESSION['count']++; }?> Building the PHP Stack for the Enterprise 11-Jun-08 10

11 About Clusters Copyright 2007, Zend Technologies Inc.

12 The single-server system As load increases Building the PHP Stack for the Enterprise 11-Jun-08 12

13 The Web Cluster Building the PHP Stack for the Enterprise 11-Jun-08 13

14 Web cluster session stickiness 1 st request 1 2 nd request 2 Building the PHP Stack for the Enterprise 11-Jun-08 14

15 Solutions for synchronizing PHP sessions in a cluster Copyright 2007, Zend Technologies Inc.

16 Load Balancer Maintain session by synchronizing between the user s browser IP address and a destination server in the cluster. The drawback: IP address may change in the midst of session If the user is behind a NAT, the actual IP can t be determined Fluctuations in load as users are permanently directed to the same destination server. Sustaining session validation over a period of time will impose heavy load on the LB memory Limited memory capacity leads to leaky bucket behavior in peak load Building the PHP Stack for the Enterprise 11-Jun-08 16

17 NFS Sharing sessions across the cluster using a Network File System Session data is centrally stored in the NFS and is served upon request to any Web server in the cluster The drawback: Limited scalability due to the NFS protocol poor performance Single point of failure Data corruption due to NFS locking mechanism Security concerns Building the PHP Stack for the Enterprise 11-Jun-08 17

18 Database The database solution alleviates data integrity Drawback: Limited scalability due to exponential increase in overhead and complexity Degraded performance Additional administration required Single point of failure Building the PHP Stack for the Enterprise 11-Jun-08 18

19 MemcacheD MemcacheD is a distributed open source memory cache Disadvantages: Doesn t transparently integrate with PHP needs API non-persistent storage Huge memory requirements Usually used as a front-end cache to DB, therefore suffers from all it s inherent problems with better performance Failures affect a % of users now, and not everyone like in the DB example Building the PHP Stack for the Enterprise 11-Jun-08 19

20 The single most important weakness shared by most of these solutions is: Failing to distribute the session data itself but rather storing it centrally! Building the PHP Stack for the Enterprise 11-Jun-08 20

21 Zend Session Clustering Copyright 2007, Zend Technologies Inc.

22 Distributing session data The Main concept: Distribute the sessions data in the cluster! ZP session clustering Building the PHP Stack for the Enterprise 11-Jun-08 22

23 Zend Platform Cluster Architecture No Change to your PHP application is required to support Clustering Each session can be accessed by every other computer in the cluster No single point of failure in HA mode, Fault tolerant mode supported Fast Performance (up to 4 times faster then DB or NFS stored sessions) Building the PHP Stack for the Enterprise 11-Jun-08 23

24 Speed and Recovery Session data can be saved to memory or to disk Save to memory for speed At least X4 faster than NFS/Database Save to disk for fault tolerance HA mode for fault tolerance In case of server failure Building the PHP Stack for the Enterprise 11-Jun-08 24

25 Inside ZP session clustering Sessions reside in the computers where they were first created Each session can be accessed by any computer in the cluster Session data is maintained by the last server to request it The overhead is a constant and it doesn t grow with increasing numbers of servers in the cluster Benefits: No Bottlenecks No single point of failure Linear scalability Building the PHP Stack for the Enterprise 11-Jun-08 25

26 Zend platform session clustering allows PHP applications to scale and remain credible in high-end workloads. For more information visit: Building the PHP Stack for the Enterprise 11-Jun-08 26

27 Zend Platform Solution Domains Complete Web Production Management Performance Scalability Reliability Run-time Code Optimization Code Acceleration and Pre-Compilation Full Caching Solution Download Optimization and Acceleration Benchmarking and Insight Validation Performance Tuning High Availability Session Clustering Central Hub-and- Spoke Management PHP Event Consolidation Clone Configurations Centralized PHP Configuration Job Queues Web-based Management Proactive Monitoring, PHP Intelligence Run-time Profiling and Performance Monitoring Report and Track Run-time Issues Audit trail (Error Re-creation and Full Problem Context Online Debugging Building the PHP Stack for the Enterprise 11-Jun-08 27

28 Zend Professional Services Support, Training and Best Practices..from Architecture Cluster Environment Support Complete Solutions Design Support..into Development PHP Framework Best Practices Custom PHP Extensions Mission-Critical Development Architecture Development Optimization Zend Consulting Services..to Optimization Performance, and Architecture Optimization Security Audits and Compliance PHP/Java Integrations 11-Jun-08 Building the PHP Stack for the Enterprise 11-Jun-08 # 28 28

29 Next Steps and Q/A For additional information on Zend s solutions to support your PHP development and production applications: sales@zend.com Phone: 888-PHP-ZEND ( ) Building the PHP Stack for the Enterprise 11-Jun-08 29

30 Questions Copyright 2007, Zend Technologies Inc.