In-depth understanding of PHP and database high availability architecture

In today's Internet era, PHP, as a widely used Web development language, greatly facilitates the work of developers and programmers. Similarly, database, as a way of data storage, is also an essential part of web development. However, with the continuous growth of website traffic and data volume, how to ensure the high availability of PHP and database has become a problem that developers need to seriously consider and solve.

I. Concept

First, we need to understand what high availability is. The so-called high availability means that the overall operation of the system will not be affected by the failure or downtime of a certain component during long-term operation of the system or service, thus ensuring the availability of system services. Therefore, for web developers, the high availability of PHP and database refers to the ability to maintain the normal operation of the entire web service when some components fail or are down.

II. PHP High Availability Architecture

1. Load Balancing

Load balancing refers to distributing Web requests to multiple servers for processing, thereby improving Web Server availability and performance. Generally speaking, load balancing can adopt two methods: hardware load balancing and software load balancing.

Hardware load balancing: Use dedicated load balancing equipment to physically distribute Web requests to different servers for processing. For example: F5, H3C, etc.

Software load balancing: Use software for web request load balancing, usually LVS, Nginx, HAProxy, etc.

When deploying PHP's high-availability architecture, load balancing can be achieved using a front-end proxy. Use Nginx as a load balancing front-end proxy to distribute web requests to multiple web servers for processing.

2. Highly available Web server

In order to improve the availability of Web services, it is necessary to configure multiple Web servers in the network and distribute the entire service to multiple Web servers. When deploying multiple web servers, you can deploy them in LAMP, LAPP or LNMP.

LAMP：Linux Apache MySQL PHP

LAPP：Linux Apache PostgreSQL PHP

LNMP：Linux Nginx MySQL PHP or PostgreSQL

Among them, Nginx is used as an alternative to Apach The front-end proxy and load balancer can handle more concurrent requests and have higher performance.

3. Storage cluster

Storage cluster refers to combining multiple storage devices into a shared memory, and then allocating the memory to multiple Web servers through a specific protocol. In this way, all web servers can access the same data, improving the flexibility and availability of the web system.

There are many ways to implement storage clusters, the more common of which is through distributed file systems (such as GlusterFS, Ceph, etc.) or distributed block storage systems (such as DRBD, GFS, etc.).

III. Database high availability architecture

1. Database master-slave replication architecture

Database master-slave replication architecture refers to writing data to the main server, The data is then copied to one or more slave servers, and the slave servers perform read operations by reading the copied data.

When deploying the master-slave replication architecture, you need to set the master-slave replication to asynchronous mode, so that the read operations of the slave server do not affect the write operations of the master server. When the master server goes down, the slave server can take over the read operations of the master server and synchronize the data to the restored master server. MySQL's master-slave replication architecture is commonly used, including Master-Slave replication and Master-Master replication.

2. Database master-slave cluster architecture

Database master-slave cluster refers to a cluster that uses multiple master servers to implement high-availability databases, improving the performance of data reading and writing. and availability. The specific implementation method can be a combination of MySQL and Galera Cluster.

In the master-slave cluster architecture, Galera Cluster was chosen mainly because it uses multi-master replication technology to achieve real-time data replication and synchronization between multiple servers. Therefore, when one of the main servers fails, the other main server can be easily used as the main server to continue to provide database services.

IV. Conclusion

In Web development, the high availability architecture of PHP and database can increase the availability and flexibility of the entire Web system and improve the productivity of Web developers. By properly deploying technologies such as load balancing, high-availability web servers, storage clusters, and database master-slave replication to achieve a high-availability architecture, single points of failure can be effectively avoided and system performance improved.

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