CD Drives facing upwards?

[Spelunx]

Hello all, I'm looking into getting a rackmount case (3 or 4u) when I realised I might run into trouble from my DVD burner. Is it possible to have a drive facing upwards (towards the sky, not lying vertically like some might assume) and have it still read/write properly?
I was thinking that I might run into problems from gravity and turning my burner into a coaster machine.
If that's the case I was wondering if I were to get a laptop dvd-burner instead would that solve my problems? I would go laptop burner because the cd is stuck to the drive via the cutout in the middle of the cd whereas a normal drive it sits in the tray with an appreciable amount of wiggle room.
Any ideas?

 

[tdg]

Many drives have the option to be vertically mounted, thats why some drives you see have little tabs or fingers at 4 points around the disc, to hold the disc until the tray retracts.

 

[Spelunx]

So basically it becomes dependent upon the type of drive I own?
As far as a drive being mounted facing up it shouldn't have any issues playing the CD/DVD?