Page life expectancy.

[dougsyer]

Id add page life expectancy along with disk counters in this article for sql servers. and if you so. Sql report do something like these counters in this article.

Also recommend adding addition disk counters for exchange servers. Not necessary to asmdd more disk counters than what you have today for most other servers.

Im not deep with sql but as far as I can tell for us the info in this article seems accurate in production but not sure about 2012.

https://www.simple-talk.com/sql/database-administration/great-sql-server-debates-buffer-cache-hit-ratio/