TMG capacity planning disks & logs

Hi,

Just finished with the TMG Capacity Planning Tool (http://www.microsoft.com/en-us/download/details.aspx?id=15196) for an array configuration.

However, its not clear what size disks will be required for Caching.

The result came back as follows:

• Number of disks for web caching per server: 2
• disk size for logging per server per day: 67 Gb

Does the Capacity Tool assume that the 'logs' and 'caching' will be stored on the same disk? Isn't it recommended for large deployments (10,000+) to separate the 'logs' from 'caching' and even implementing some form of RAID for caching?

Thank you,

SK