Thank you both for the reply.
M_DISKS is good but it goves the filesystem size as it is. The different is too much between the filesystem size vs the table on disk. There is another view in System Information tab, size of the table on disk. This gives all the the tables on disk. I have seen the some tables are missed in M_CS_TABLES.
Anyways this is not very straight forward.
But one observation is that size of the fully loaded table was much less on memory then on disk. This means that data was further compressed before loading it into memory. Is it correct stament.
Regards,
SS