Beginner: (Stand-alone mode)
Hypothetical configuration: (Dual core 2.0GHZ,4GB RAM,SSD)
Basic Framework: Apache (PHP) + Mysql/iis + MSSQL
(most basic framework for handling general access requests)
Advanced 1: Replace Apache as Nginx and add the cache layer to the database.The speed of the database is the biggest bottleneck"
Nginx (PHP) + Memcache + Mysql
(you have the ability to handle small traffic at this time)
Advanced 2: With the increase in traffic, the first problem comes: CGI cannot match the high IO performance of nginx, this time can write extension to replace the script program to improve performance, C extension is a good way, but people prefer to complete the task in a simple scripting language, Taobao team Open Source A Nginx_lua module, you can use LUA to write Nginx extension, this time can handle the concurrency has surpassed the advanced 11 grade.
Nginx (Nginx_lua or C) + Memcache + Mysql
(at this time processing a simultaneous online three thousand or four thousand people no problem)
Advanced 3: With the increase of users, MySQL writing speed has become another big bottleneck, read memcache do cache, but the write is directly facing MySQL, performance is greatly hindered, at this time, to add a layer of write cache between Nginx and MySQL, the queue system on the appearance, Take RABBITMQ as an example, all write operations are thrown into the rabbit's stomach, and then the back of the buttocks to write a pick-up program, a strip of pull out and then write to MySQL. While the RABBITMQ write efficiency is the N-fold of MySQL, this time the structure of the processing power of a class.
|----Write------>RABBITMQ--------
Nginx (LUA or c)-----|--------->mysql
|----Read------>memcache--------
(at this time the concurrent throughput capacity can be handled by the million people online)
Intermediate article: (Divide and conquer)
At this point we are in the single-machine optimization has reached the limit, the next cluster to show the role.
Database article:The database is always the weakest in the whole process, the most common method is sharding.
sharding can be divided in a variety of ways, no stereotypes, see the situation. Can be divided by User ID section, according to read and write points, and so on, available reference software: MySQL proxy (works like LVS)
Cache Chapter:memcache is generally used to build memcache pool, the cache is scattered across multiple memcache nodes, how to distribute the cache data evenly across the nodes, the general use of the sequence number of nodes, and then hash to the rest of the corresponding to the node up. This allows for a more homogeneous dispersion, but one of the deadly points is that if the number of nodes increases or decreases, there will be almost 80% of data migrations, and the solution we'll mention in the advanced article.
Web server article:Web server cluster construction, the most common is the LVS way (Memcache pool can also be set up), the core of LVS is the dispatch node, the dispatch node is responsible for the flow through the algorithm dispersed to the various nodes, because the scheduling consumes less resources, so can produce very high throughput rate, The number of background nodes can be arbitrarily additions and deletions, but this method is the drawback if the scheduling node is hung, the entire cluster is hung, the solution we in the high-level article.
Method 2: SeeHaproxy-the Reliable, high performance tcp/http Load Balancer
Advanced article: (High availability + highly scalable cluster)
single point scheduling fault resolution:
The benefits of clustering are obvious, but one drawback is that single-node scheduling, if the node fails, the entire cluster can not serve, the solution to this, we usekeepalivedto solve. Keepalived for Linux
Keepalived is based on the VRRP protocol (VRRP Protocol Introduction), be sure to understand the VRRP protocol before you configure it.
keepalived can make multiple devices virtual one IP, and automatically between the fault node and the standby node to achieve failover switch. In this way we configure two units of the LVS scheduling node, and then configure the keepalived can be done after the LVS scheduling node failure, automatically switch to the standby scheduling node. (same for MySQL)
memcache Cluster Expansion solution:
Memcache because we generally use the hash after divided by the number of nodes to take the remainder, and then allocated to the corresponding node, if the number of nodes changes, the previous cache data will not be hit basically.
WORKAROUND: Consistent hashing Introduction:Consistent Hash
consistent hashing The approximate idea is that the value after the hash is guaranteed to 0 ~ (2^32)-1 of the values, and then the series of numbers mapped to an imaginary circle.
hash the values to be stored, put them on a circle,
then the cache node is also used the same hash method, mapped to the circle, and then each hash value just now clockwise to find the nearest node, this node is the node that stores it.
in order to improve the balance of storage, the algorithm can also join the concept of virtual node, that is, each actual cache node, will be on the circle corresponding to n virtual nodes, which can improve the algorithm hit ratio, more balanced.
Consistent hashing principle:Consistent hashing and random trees
end.
Server Configuration beginner and advanced
