How much should be the data file size..?

[skdas]

1. I have to create a tablespace of 19Gb size.

2. How much should be each data file size..? Any guide line documents..?

[slimdave]

You'll probably want to spread the i/o across your devices, so the minimum number of files should probably be equal to the number of disk arrays.

Also, you'll want to keep the data file size manageable should you want to move them around.

Generally people go for 2Gb or 4Gb -- in your case i would say 4x4Gb + 1x3Gb. Might as wel make is 5x4Gb really.

[dasari98]

There is no limitation as to what size u'r datafile should be.
you can have a 19*1 .

data file size manageable should you want to move them around.

4GB*5 should be appropriate.

U should also consider if u'r o/s handles large files without any i/o
issues.