'Buffers',# RH6: temporary storage for raw disk blocks.
'Cached',# RH6: physical RAM used as cache memory.
'SwapCached',# RH6: memory that has once been moved into swap, then back into the main memory, but still also remains in the swapfile. This saves I/O, because the memory does not need to be moved into swap again.
'Active',# RH6: buffer or page cache memory that is in active use. This is memory that has been recently used and is usually not reclaimed for other purposes.
'Inactive',# RH6: buffer or page cache memory that are free and and available. This is memory that has not been recently used and can be reclaimed for other purposes.
'Dirty',# RH6: waiting to be written back to the disk.
'Writeback',# RH6: actively being written back to the disk.