Mac doesn't recognize USB HD at boot time

Question

Level 1

0 points

Mac doesn't recognize USB HD at boot time

Hello all,

I have a little 2.5'' USB HD (30 GB Datalux). When connect it while the
computer is on, everything works fine.

But when the device is allready conncted before I turn on the computer it doesn't work. It is shown as a "USB Mass storage device" in the system profiler and the disc utility also shows the drive, but not the parition on it. No icon in the finder. The LED on the drives is on and I can hear the drive rotating.

When I pull of the cable and put it back in after a few seconds it works correctly and I get the icon in the finder.

This is the same on two Macs (Intel MacBook Core Duo and iMac G5 Rev.A).

I would like to leave the drive connected to the iMac most of the time, but this doesn't work because of this problem.

Christian

MacBook 2GHz, iMac G5, Mac OS X (10.4.7)

Posted on Dec 26, 2006 4:36 AM

Reply

Answer 1

a brody

Level 10

82,825 points

Dec 26, 2006 6:25 AM in response to Christian_k

USB drives won't boot PowerPC Macs into Mac OS X. Some Mac OS 9 bootable Macs can boot off of USB into Mac OS 9, but the iMac G5 is not Mac OS 9 bootable.

Some USB drives are capable of booting Intel Macs, but only those with the right firmware. Firewire is much more capable at booting both Macs. There is also a firmware caveat with Firewire booting, which is discussed on my FAQ:

http://www.macmaps.com/firewirebug2.html

Be sure any such data is backed up elsewhere before you attempt to boot off such a drive.

Note, an Intel Mac will not off a PowerPC formatted drive either. The drive needs to be GUID formatted. This tip explains how to develop a dual boot system for Intel and PowerPC:

http://www.macosxhints.com/comment.php?mode=view&cid=80537&query=Intel%20PowerPC

You might be able to find out which USB drives are capable of booting Intel Macs on this website:

http://www.xlr8yourmac.com/

Reply

Answer 2

Christian_k Author

Level 1

0 points

Dec 26, 2006 8:43 AM in response to a brody

Thank you for your answer, but we are talking about two different things.

I just want the mac to recognize the drive when the USB cable is allready connected before the machine is switched on.

The drive only works when it is connected later when OSX is allready running, no icon in the finder otherwise.

I am not trying to boot from the external at all.

Christian

Reply

Answer 3

a brody

Level 10

82,825 points

Dec 26, 2006 9:13 AM in response to Christian_k

Is the USB drive self powered, or bus powered?

Reply

Answer 4

Christian_k Author

Level 1

0 points

Dec 27, 2006 10:15 AM in response to a brody

bus powered (2.5'' HD), no external power supply.

Christian

Reply

Answer 5

a brody

Level 10

82,825 points

Dec 27, 2006 1:26 PM in response to Christian_k

Some third party bus drives need extra power to be recognized after the machine wakes from Energy Saver. It would suggest, the low power of being off has the same trouble with this drive. I'd contact the manufacturer and ask them to find out Apple's specs for being recognized at boot for bus powered devices.

Reply