Chapter 1 squid Chinese authoritative guide

From: http://bbs.chinaunix.net/viewthread.php? Tid = 561395

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I have maintained several squid servers at work. I have read Duane Wessels (he is also the founder of squid) for many times. His original title is "Squid: the definitive guide ", published by o'reilly. I have translated it into Chinese in my spare time, hoping to help Chinese squid users. For common Internet users, squid can be used as a contemporary server, while squid acts as a Web Accelerator for large sites such as Sina and Netease. Both roles play exceptionally well. The open-source world is as beautiful as the stars, and squid is one of the dazzling stars.
Please contact me if you have any questions about this edition. My email is: yonghua_peng@yahoo.com.cn Peng Yonghua

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The first chapter is the brief description of squid, which has little to do with technology. I don't want to translate more.

1.1 Web Cache

In this section, we need to understand three concepts:

Cache hit-occurs every time squid satisfies HTTP requests from its cache. Cache hit rate, which is the percentage of hits among all HTTP requests. The typical cache hit rate of Web Cache is between 30% and 60%. Another similar measurement unit is the byte hit rate, which depicts the data capacity (in bytes) provided by the cache ).

Cache loss-occurs when squid cannot satisfy HTTP requests from its cache. There are many reasons for cache loss. Most obviously, when squid receives a request for special resources for the first time, it is a cache loss. Similarly, squid clears the cache to release space for new objects. In addition, the resource cannot be reached. The original server instructs the cache on how to handle the response. For example, it prompts that the data cannot be cached or used repeatedly within a limited period of time.

Cache Validation-ensure that squid does not return outdated data to users. When the cached object is reused, squid often confirms it from the original server. If the server indicates that the copy of squid is still valid, the data will be sent out. Otherwise, squid upgrades its cache copy and forwards it to the customer.

1.2 Brief History of squid

If you are interested in this section, please read the original English document.

1.3 hardware and Operating System Requirements

Squid runs on all popular UNIX systems or Microsoft Windows. Although squid's Windows support is constantly improving, it may be easier on UNIX. If you have a favorite operating system, I suggest you use it. Otherwise, if you are looking for recommendations, I like FreeBSD very much.

Squid does not have high hardware requirements. Memory is the most important resource. Memory shortage seriously affects performance. Disk space is another important factor. More disk space means more cache targets and higher hit rates. Fast disks and drives are also advantageous. If you are willing to spend money, the SCSI disk performs better than ATA. Of course, fast CPU is also good, but it is not a key factor to improve performance.

Because squid uses a small amount of memory for each cache response, there is a certain relationship between disk space and memory requirements. The basic rule is that each GB of disk space requires 32 MB of memory. In this way, a 512 M memory system supports 16 GB disk cache. Of course, your situation will be different. The memory requirement depends on the fact that the cache target size, the CPU system (32-bit or 64-bit), the number of online users at the same time, and the special features you use.

People often ask this question: "I have X users on the network. What kind of hardware is required for squid ?" For many reasons, such a question is hard to answer. In particular, it is hard to say how much traffic X users will generate. I told people to build a system with enough disk space to store web traffic data for 3-7 days. For example, if your user consumes 1 m of traffic (HTTP and FTP transmission only) eight hours a day, it is about 3.5 GB a day. Therefore, I can say that each MB of web transmission requires 10 to 25 GB disk space.

1.4 squid is open-source

Squid is a free software and cooperation project. If you think squid is useful, consider one or more of the following methods to return the project:
1. Participate in the squid user discussion list, answer questions and help new users.
2. test the new version and report bugs or other problems.
3. Committed to online documentation and FAQs. If you find an error, report it to the maintainer.
4. Submit your local modifications to the developer.
5. Provide financial support to developers.
6. Tell the developer about the new features you want.
7. Tell your friends and classmates that squid is cool.

Squid is a free software issued under the GNU Public License (GPL. For more information about GPL, see http://www.gnu.org/licenses/gpl-faq.html.

1.5 Squid Web Homepage

Squid home page in http://www.squid-cache.org you read this site by yourself.

1.6 get help

1.6.1 FAQ

Squid FAQ documentation in http://www.squid-cache.org/Doc/FAQ/FAQ.html is a good information resource for new users.

1.6.2 email list

Squid has three email lists available. Mail list home page at: http://www.squid-cache.org/mailing-lists.html

1.6.2.1 squid user

Subscribe to this list of emails to the squid-users-subscribe@squid-cache.org

1.6.2.2 squid announcement

Subscribe to this list of emails to the squid-announce-subscribe@squid-cache.org

1.6.2.3 squid Development

This email list is restricted. Its content is published in http://www.squid-cache.org/mail-archive/squid-dev/

1.6.3 career support

Pay-as-you-go support-Career Support Service Provider list, see http://www.squid-cache.org/Support/services.html

1.7 start squid

Please refer to the following chapter step by step.