http://www.idera.com/News/Newsletters/Quick-Tips-for-Mnging-SP2010-Office-Web-Apps-Cache.pdf
The Office Web Apps Cache Creation timer job creates an Office_Viewing_Service_Cache site collection in a content database that is collocated with one or more of the “real” site collections within each of your content Web applications. Since the cache site collection is allowed to grow by default to a beefy 100GB, it makes sense to relocate the cache site collection to its own (new) content database. Relocating the cache site collection to its own content
When an Office_Viewing_Service_Cache site collection is provisioned within a Web application by the Office Web Apps Cache Creation timer job, it is initially configured to hold cached document resources for 30 days. As mentioned in Tip No. 1, a cache site collection can also grow by default to a maximum of 100GB.
database makes it easier to exclude it from other maintenance, such as backups.
When an Office_Viewing_Service_Cache site collection is provisioned within a Web application by the Office Web Apps Cache Creation timer job, it is initially configured to hold cached document resources for 30 days. As mentioned in Tip No. 1, a cache site collection can also grow by default to a maximum of 100GB.
