Need info about --in-memory option

Hi All, I am new to MonetDB and this is my first email to this group. I came across the option --in-memory for mserver5. I understood that if this option is set, then MonetDB operates out of memory and data is not persisted. I wanted to know more details about the working of MonetDB if this option is set: 1. If this option is set, what is the maximum data size that MonetDB can operate with? 2. If this option is set, will MonetDB use mmap only for reading purposes or not use mmap at all? Any other information is really welcome. Thanks in advance. Lakshmi Pathy S N