That advice is a little out of date, specially in the future world of 0.8 memory management, see http://thelastpickle.com/2011/05/04/How-are-Memtables-measured/

Cheers
-----------------
Aaron Morton
Freelance Cassandra Developer
@aaronmorton
http://www.thelastpickle.com

On 6/07/2011, at 5:51 PM, Donna Li <donna.li@utstar.com> wrote:

All:

For a rough rule of thumb, Cassandra's internal datastructures will require about memtable_throughput_in_mb * 3 * number of hot CFs + 1G + internal caches.

 

Why cassandra need so much memory? What is the 1G memory used for?

 

 

Best Regards

Donna li