Enable caching

To enable caching

In the console tree of ISA Server Management, click Cache.
In the details pane, click the Cache Drives tab and select the applicable drive.
On the Tasks tab, click Define Cache Drives (Enable Caching).
Select one of the drives listed.
In Maximum cache size (MB), type the amount of space on the selected drive to allocate for caching.

Notes

For more information about ISA Server caching, see Caching Concepts in ISA Server 2006 at the Microsoft ISA Server TechCenter Web site (http://www.microsoft.com).
To open ISA Server Management, click Start, point to All Programs, point to Microsoft ISA Server, and then click ISA Server Management.
For ISA Server 2006 Enterprise Edition, expand Microsoft Internet Security and Acceleration Server 2006, expand Arrays, expand Array_Name, expand Configuration, and then click Cache.
For ISA Server 2006 Standard Edition, expand Microsoft Internet Security and Acceleration Server 2006, expand Server_Name, expand Configuration, and then click Cache.

Important

Caching is enabled only when the size of at least one cache drive is greater than zero.
When the Microsoft Firewall service is stopped, cache drives cannot be defined or modified, and caching cannot be enabled in ISA Server Management.
After you enable caching, you can check that caching is functioning as expected by monitoring the ISA Server Cache performance counter.
When you configure a drive for caching, ISA Server creates a cache content file (Dir1.cdat) in the drive:\urlcache folder. You can specify an alternative cache file location on the drive, including an environment variable such as %cacheDirectory%. If the specified folder does not exist, ISA Server will warn you that the specified location is not valid and will try to create the folder.
To disable caching, click Disable Caching.

Get latest ISA Server content at ISA Server Guidance(http://www.microsoft.com/).