Thanks for the information. Well, any time you plug an external storage device into your Mac, you will have an extra icon appear in your Finder (at top left just under the Macintosh HD icon) where you can click on the device to browse the contents of it, just like you can for your Macintosh HD icon. So that you're not confusing the Mac, you need to click the Eject button next to the icon that appears for your Rocstor storage device so that the Mac knows you are about to sever the connection between it and the Mac. In geek speak - when clicking the eject button, you're unmounting the volume, also known as the Rocstor device.
After time, I've seen folks that consistently do not click the eject button (before unplugging the firewire cable to their external storage device) have problems getting the device to show up in Finder again.
Depending on whether you're using a USB or Firewire cable to connect your Mac to the Rocstor, it's been said that one of the USB ports on Macs actually provides more power to the external device over the others. So, if you've plugged the Rocstor into one of the USB ports and it doesn't show up, unplug it, then plug it into a different USB port.
Lastly, if none of this works, you can try unplugging the Rocstor and performing repair disk in Disk Utility, reboot your computer, then plug the Rocstor back into the Mac. Here are the steps for this procedure:
Repairing Disk Permissions
1) Close any/all applications, programs, etc.
2) Open the Disk Utility by selecting Applications -> Utilities -> and then Disk Utility
3) From the left pane toward the top, select Macintosh HD (or whatever name you've called it if changed from default)
4) From the right pane toward the bottom, select the "Repair Disk Permissions" button. Once complete, reboot your Mac.
Note: This process can take anywhere from 10 minutes to an hour or so. Things that can affect the time it takes Repair Disk Permissions to complete:
* Whether you've run Repair Disk Permissions or not
* How fast your computer is
From my experience, I've seen this utility fix all sorts of issues - anywhere from Applications/Utilities not launching or responding to Mac computers not booting properly. Because of this, I recommend you do this once every couple of months and any time you perform an Apple Software Update.
For future reference, here is a screenshot of my Finder with an external hard drive plugged in. You should see something similar to yours.
If you'll notice, at the top left, I have two storage devices. The one that came with the Mac which is the internal hard drive called Macintosh HD. The one directly beneath it is 2TB which is an external storage device connected via USB. Directly to the right of 2TB is an eject symbol. If I were to take my laptop elsewhere, I would click this eject button before disconnecting the external storage device and the Mac would know to unmount this volume and gracefully sever the connection.If the information I've provided meets with your approval and resolves your issue, please let me know and you can Accept the answer (and if possible, leave positive feedback). If not, please DO NOT Accept the answer. Instead, let me know what happened and we'll try some more things or I can refer you to another Expert who may be able to help you further.
Edited by loadedmind on 5/1/2010 at 4:19 PM EST