When you create a database, you set the size and reserve size in MB of the initial IQ database file (the IQ_SYSTEM_MAIN dbspace).
For raw partitions, you do not need to specify IQ SIZE or TEMPORARY SIZE; Sybase IQ determines the size of the raw devices and sets IQ SIZE and TEMPORARY SIZE automatically. If you do specify size, the size cannot be larger than the actual raw partition size.
For operating system files you can rely on the defaults or specify a value based on the size of your data, from the required minimums up to a maximum of 4TB, in 1MB increments.