Db Block Gets — The number of blocks accessed via single block gets (not through the consistent get mechanism).

Consistent Gets — The number of accesses made to the block buffer to retrieve data in a consistent mode.

Physical Reads — The cumulative number of blocks read from disk.

Buffer Cache Hit Ratio — The rate at which the database goes to the buffer instead of the hard disk to retrieve data. A low ratio suggests more RAM should be added to the system.