In pictures: Taking apart Hewlett-Packard's Prolia...
Disks are easily removed by pressing the red button to unlock the drive, then pulling on the handle that pops up. Each drive has two status lights below the button that let the user see what the drive is doing. The online LED is the left, while the right LED will flash green, amber or blue to indicate activity, faults or identification, respectively.
In pictures: Taking apart Hewlett-Packard's Proliant DL380 G5 server