Orientation refers to how the hard disk drive is physically installed into the
PC. In the majority of cases the drive is installed in the "default" way: flat,
with the drive parallel to the ground, the logic board facing down and the drive label
facing the sky. Some PC cases, however, especially the smaller desktop boxes, have
side-mounted hard disk bays. Either of these orientations is common and should present no
problems. In fact, most manufacturers say that you can mount their drives any way you
wish, even upside-down if it is necessary. That said, my personal opinion--one shared by
at least one manufacturer--is that you should avoid strange mounting positions if it all
possible. The reason is simple: most testing of drives is done with them in either of the
standard orientations. Hard drive manufacturers don't do nearly as much testing of drives
mounted upside-down as they do of drives right-side up. For the sake of reliability, it's
best to keep things simple if at all possible, and well, go with the flow.
Older hard disks that used stepper motor actuators were
much more sensitive to orientation. It was in fact often recommended that the low-level
formatting of the disk always be done after the disk was installed in its operating
position, to avoid any shifting of the location of the tracks that might be caused by
changing the orientation. Since hard disks today are much more solidly built, and they use
voice coil actuators for dynamic head positioning, this really is
not an issue. A modern hard disk can be side-mounted in the case without any problems, and
can also have its orientation changed after it has been in use for some time.

|
Mounting holes on a SCSI hard disk, viewed from the
bottom of the
drive. The one at left is part of the set of holes used if putting the mounting
screws into the bottom of the drive; the one at right is for side mounting. |
Most hard disks have screw holes built right into the aluminum base of the disk itself.
They can usually be mounted by screwing into the bottom of the base, or the side. There
are some caveats here. First, make sure you use small screws, preferably the ones that
came with the hard disk--using ones that are too long can in theory damage the drive.
Second, since the circuit board is exposed, it must be carefully watched to ensure that
there is no chance that it will be contacting anything when the drive is installed, or the
logic board could be shorted out.
Next: Drive Rails and Mounting Kits