Oracle version 7,only 1,022 datafiles per database could be used.

Oracle version 11g,support 65,533 datafiles per tablespace.

With ASM you can have 63 disk groups with 10,000 ASM disks in it,where each ASM disk can store up to 2TB of data. A disk group can handle one million ASM files. The maximum supported file size for a datafile in Oracle Database 11g is 128TB,whereas ASM supports up to 140PB with external redundancy,42PB with normal redundancy,and 15PB with high redundancy.