Can you boot a Mac Pro using a USB Pen Drive?

Yes, you can boot OS X from a USB flash drive on any Intel Mac provided the flash drive uses the GUID partition scheme and is formatted Mac OS Extended (Journaled.)

Windows should boot if you have installed the requisite Boot Camp drivers. Not sure about other systems unless they are known to boot an EFI-based machine like the Intel Macs.

Actually, having the Boot Camp drivers has no bearing on whether or not Windows will boot. Mac Pro's require the updated ROM to be installed in order to boot any BIOS-based OS (Linux/Windows) but, as far as I know, this ROM update is already applied to all Mac Pro's.

I would be cautious in saying that you can, in fact, boot Mac Pro's from USB thumbdrives. While booting OS X off a GPT partitioned thumbdrive might work, I can verify that booting Linux or Windows off a thumbdrive does not work on Mac Pros. It works on my Core Duo iMac but not on my Mac Pro. Either with rEFIt or by using the option-key method.

Read my post carefully. Note that I stated I wasn't sure about booting from LInux. You can boot any Intel Mac from a properly partitioned and formatted flash drive. I did not say that the Boot Camp drivers were needed for Windows to boot, but they are needed for Windows to properly interact with the Mac hardware.

I've had no problems booting my Intel Macs from flash drives. These include two MBPs, one MB, one iMac, and a Mac Pro.

Not to get in to an argument over semantics here, but by saying "Windows should boot if you have installed the requisite Boot Camp drivers," you are implying "that the Boot Camp drivers [are] needed for Windows to boot." I was just clarifying your post so people didn't get confused.

As for booting a Mac Pro off a USB flash drive, if you have been successful in doing so, can you share with me your method? I've tried booting of an OCZ Rally2 4GB flash drive and it's never worked on my Mac Pro. It doesn't show up when I hold option down and if I try to boot through rEFIt, I get an error about my Mac's firmware not supporting USB booting (I have the latest firmware installed, too). I've tried GPT and MBR partitions, both to no avail. Booting off USB hard disk drives is no problem though. And I can boot off this flash drive on a Core Duo iMac.

Any ideas?

If you install rEFIt, it will present to you a graphical listing of all bootable disks (including Linux) at startup. However, as I pointed out in another post in this thread, on my Mac Pro, I am never able to boot up from a USB flash drive into Linux--only USB hard disk drives.

http://refit.sourceforge.net/

You can install OS X on the flash drive directly. The drive must be re-partitioned using the GUID partition scheme and reformatted using Mac OS Extended (Journaled.) That's all that is required. Of course you must install the Intel version of Tiger or install Leopard. Your installation must be kept small enough to fit on the flash drive. For practical reasons an 8 GB flash drive is the best to use. You can create a smaller version by installing first on a disc image then paring the installation down to a size that will fit on a 4 GB flash unit, then use the Restore option of Disk Utility to put the disc image onto the flash drive.

Sorry I thought we were talking about booting OSes other than OS X. I can boot OS X off a thumbdrive on my Mac Pro but not Linux or Windows.

I just did another test on my Mac Pro to confirm my past experiences. Two separate USB Thumbdrives one with a MBR partition table and another with a GPT partition table. Both have Ubuntu Linux installed. Cannot boot up the Mac Pro with either USB drive either using rEFIt or by using Apple's booloader (holding down option). I'm assuming this would be the same effect if Windows were installed.

This is really annoying because I have a Core Duo iMac where Ubuntu boots perfectly off a USB flash drive. Grrrrrrr...

How did you get Ubuntu to boot from a flash drive on your iMac?

Hey. Didn't notice anyone had replied to the thread. Anyway, I just installed Ubuntu (and have also tested with Arch Linux) by booting up the iMac (also tested now with a MacBook) using the Linux livecd.

When prompted for an installation location, select the USB device as your drive and allow it to do auto partitioning. Make sure GRUB gets installed on the root of the device (ie sda or sdb) and not a partition (ie sda1 or sdb2).

Then install rEFIt and allow it to boot your Mac off the USB drive.

Oh yeah, and I still cannot get my Mac Pro to boot up using USB flash drive with Linux on it.

Works fine on MacBook/iMac.

Has anyone got a Mac Pro that they can succesfully boot up using Linux on a USB flash drive?