When you configure a drive for caching, Forefront TMG creates a cache content file on that drive with the .cdat extension. A file, named Dir1.cdat, is created in the <drive>:\urlcache folder.
There is a cache content file for each 10 GB of space on a disk, to the maximum that you dedicated for the cache. For example, if you allocate 12 GBs of disk space on a particular drive, Forefront TMG creates two cache content files. The first file will be 10 GBs and the second file will be 2 GB.
As objects are cached, Forefront TMG appends them to the cache content file. If the cache content file is too full to hold a new object, Forefront TMG removes older objects from the cache, by using a formula that evaluates age, how often the object is accessed, and size.
All of the content stored in the Forefront TMG cache can be deleted by stopping the Microsoft Firewall service and then deleting all of the .cdat files on all of your cache drives. New files that do not contain any stored content will be created when the Firewall service is restarted.
Warning Do not modify cache content files, and do not delete these files when the Firewall service is running.
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Build date: 11/30/2009
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