When you install an M3 Business Engine database, all tables and indexes are created in different schemas. Tables are placed in TMVXSD and indexes in TMVXSI. The TMVXSD is created with two database files and TMVXSI has three. The ratio between storage for data and index are usually 1:2.
The database files of the M3 Business Engine tablespaces have been created with a maximum size of 10 GB and with the autoextend option. Initially they are not allocated 10 GB, but will automatically extend when the tablespace is running out of space. When a data file autoextends itself, it extends by the value of NEXT qualifier (for M3 Business Engine database files, NEXT is set to 100 MB). When the limit 10 GB has been reached for all database files, the solution is to add a new database file to the tablespace.
Never wait this long before you do it - work proactively and check empty space at least every week.
Some tables and indexes grow very fast and could be better of in its own tablespace. In the database, there are two tablespace, TMVXLD and TMVXLI, created for this purpose. Optionally, you can create your own tablespace and move them over to these instead.