Here’s a tip for anyone who would like to control what goes into and is kept out of Flash Cache.
By default, Flash Cache will cache reads of WAFL metadata and user data for all volumes behind the storage controller. You have the option to cache user data for some volumes and exclude user data for others. (WAFL metadata will always be cached for every volume).
The trick is to use FlexShare quality-of-service feature in combination with Flash Cache. In the Normal (default) and Low Priority modes of Flash Cache operation you can deny caching on a volume by volume basis. Conversely, in the Metadata mode you can enable the caching of user data on a volume by volume basis.
For more information, including the FlexShare commands to use, see TR-3832 Flash Cache and PAM Best Practices Guide. Section 3 of this technical report has the details you will need to know. Here’s a link to this report:
http://media.netapp.com/documents/tr-3832.pdf
Cheers,
Mark Woods
