Chat Web Picture Server Application Analysis _ website application

A little understanding of oneself, to be able to elicit more valuable information.

It's about storing pictures.
What media do you store the pictures in? If you have enough money to buy a dedicated picture server hardware or NAS device, it's simple; if you have the ability to develop your own file system for storing pictures separately, then you don't have to look down.

If the above conditions are not available, just want to store on the ordinary hard disk, first of all, consider the physical hard disk's actual processing capacity. is 7200 turn or 15000 turn, the actual performance difference is very big. Choose ReiserFS or EXT3, how do you want to test it? When creating the file system, the inode problem should also be considered, choose the appropriate size of the inode, in space and speed to make trade-offs, and precautions, note that a single file system under the number of files do not reach the limit.

Standalone, stand-alone server
Regardless of management, or performance, as far as possible, to deploy a stand-alone picture server. This is almost common sense (though it was a joke before I did a Web-facing project). With a stand-alone image server or server cluster, the WEB server can be targeted for configuration optimization. such as the use of legendary more efficient Lighttpd.

If you don't want to sync all the pictures between several machines, just share them with NFS mode. Note the possible problems with soft, hard connections, and NFS-specific transmission speeds.

Independent, independent domain name
If most Web pages have to load a lot of pictures, you need to be aware of the connection number of IE browsers (see the test for this problem).

A few days ago a friend asked me online, "Some big sites, picture server Why are using another domain name?" For example yahoo.com picture server uses the domain name of yimg.com? ", the rough point of the answer: In addition to easy management, convenient CDN synchronous processing, the above said IE connection number limit is also a factor to consider it (other reasons I do not know, please Yahoo! "There is another factor that I have not considered is a Cookie, take a message downstairs Gao Chunhui."

Yahoo Web Optimization 14 article
About the Yahoo YSlow tool advocated optimization 14 rules, recommended that each WEB maintenance personnel must recite, of course, should also be dialectical--introduction of the 14 rules of the page itself can only get more than 70 points ... The Nineth and above the independent domain name is somewhat contradictory. The actual situation should be based on their own Benchmark and specific needs of the determination.

Efficient use of client Cache
In order to achieve some visual effects, many Web site UI designers apply a large number of images to a number of page modules that users need to visit frequently. In this case, research shows that for users with high viscosity of the site, on the Web server for this class of objects set Expires Header is very necessary, a large amount of bandwidth so saved, the cost is also saved. By the way, for something like a captcha, add a simple rule to filter it out.

Server-Side Cache
At home, a CDN is also rich enough to afford to play. and a package of storage services like the Amazon S3 has not yet emerged in the country. Therefore, the full use of server-side Cache is also necessary. Squid as a reverse proxy server, buffer image effect should say fair, Sina technical team contribution Ncache according to the evaluation, the effect is better.

High resolution picture problem
If the site has a large number of high-resolution images, it is necessary to consider deploying iipimage or similar software.

Operational issues
Many of the more scale of the site for users to upload pictures do not do any processing, the results page can also see a lot of BMP format pictures (individuals feel that any site BMP format of the pictures are shameful) ... This is entirely a mistake in the operational strategy. Find a programmer to devote a little time to write a picture processing module, the "screenshot" of the picture to do a conversion, the cost of input may be far less than the overhead, and users visit the picture, quality may not be able to have any loss, browsing speed is undoubtedly much better. Which way of handling is more acceptable, it goes without saying.