File structure examples

OVERVIEW OF THE CACHE STRUCTURE in MS Internet Explorer 4.0

With the release of Internet Explorer 4.0 and the Internet SDK, it is expected that many different programs will take advantage of the caching support provided. This means that there could be thousands of URLs downloaded and kept in the cache.

Having thousands of URLs cached into a single directory causes performance to degrade on computers running Windows 95, which uses

the FAT file system. There are two primary reasons:

• There is a linear search algorithm (sequential) in FAT to look up a directory entry.
• The in-memory structure of the directory entry caching used by FAT does not work by directory but by individual file, causing it to access the disk more often.

This is the main reason there are multiple directories in the cache. Internet Explorer directs each URL into one of the multiple directories (buckets), where the downloaded data is kept in the form of a file. An index entry is created in the index file(s) in that directory.

Microsoft (1997, May)

[Rev 9/6/98] 2/7/97 © 1997-98 V/2-Com (Verhaart), P O Box 8415, Havelock North, New Zealand.