software RAID 1 mirror details?

[Jack Howarth]

    I have some questions regarding the proper way to 
set up a software RAID 1 mirror under Fedora on two
identical SATA drives using the installation tools.
In particular I am seeking to create a complete
RAID 1 mirror so that if the main drive fails I can
simply move it out and reboot under the mirror.
What I am unclear on is how should I partition the
two drives and how these partitions are related
in the software RAID 1 mirror.
    My first inclination is to use DiskDruid in the
installer to create identical sized partitions on
both SATA drives (three partitions each...
/boot, / and /swap). Of these I would only place the
partitions for /boot and / in the RAID. My rational
for this is that there is no point in mirroring the
/swap partition. 
    Assuming this approach is correct, I am still 
unclear on how the software RAID 1 mirror knows
which partitions on each drive to map to each other?
Does it just try to grossly map them by size and 
do they have to be of identical size on both
drives of the RAID 1 or just bigger on ther mirror?
Thanks in advance for any clarifications.
                      Jack