Putting PGSQL on several disks

Hi,
I'm new on the lists, and i apologize if this subject is out of subject.

I'm installing PostgreSQL on a 4 disks Server.
First is for System only.

And i want to install the bases on the 3 other disks:
- 1 for bases.
- 1 for rollback segs.
- 1 for log/jornaling.

But i couldn't find how to do this ...
Someone has an idea ???

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