LIS 525 - Servers

" Setting up a Web server is a trick only a certified computer geek should try."
(Kent, P. 2000. Poor Richard's Web site, 2nd ed. 54)

A server is a combination of hardware and software on a network that holds information and reponds to requests. A Web server specifically provides web services to remote clients; these services may include Web pages and secure transactions.

Backup

It is essential that server files be backed up regularly. Backup may be on local media, such as tapes, or over a network. Local backup gives greater functionality, but requires local administration. In any case, it may be difficult to restore everything from backup.

Local backup strategies should include medium rotation; for example, a backup takes place every day of the week on a different tape, with changes only backed up every day except Sunday, when a full backup is performed. Since tapes wear out, a new tape should be introduced regularly; it might be made the Monday tape, and each of the other tapes might be shifted one day, with the Sunday tape retired to the archives.

Popular Server Software

The most popular server software is Apache, at about 46% of active sites, followed by Microsoft, at about 38%, and Google's Blogger, at about 10%, with others at less than 1% each.

Netcraft has a form that you can use to find out what server a given site is running.

Some Options

Dedicated server

Virtual server

Computer resources are shared with other virtual servers running on the same machine. Allows low-cost web hosting.

Ways to Improve Server Performance

* If caching is used, it should be disabled for pages that are time-sensitive or customized for specific users; such pages are normally recognized from HTTP header information (e.g. Expires or Cache-Control headers) or from the use of HTTPS.

Arranging Multiple Servers

Method Explanation Advantages Disadvantages
DNS balancing DNS server returns different IP addresses randomly or depending on loads. Balance may be poor.
Long session may use more than one server - files must agree.
Hardware/software load balancing Front end intercepts and routes HTTP requests. Better performance than DNS.
Can detect when a server is having problems.
Reverse proxying Similar to previous, but proxy server caches some content, especially static content. Reduces load on server(s).
May be faster.
Content spreading across servers Different material on different servers, with appropriate links between pages. Some load balancing. Client's key files can be mounted on a small dedicated server. Not very dynamic. Additional cost and poor load balancing if a dedicated server is included.

For More Information


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Last updated October 31, 2007.
This page maintained by Prof. Tim Craven
E-mail (text/plain only): craven@uwo.ca
Faculty of Information and Media Studies
University of Western Ontario,
London, Ontario
Canada, N6A 5B7