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shihyuan
6th February 2009, 09:39 AM
Hi,

I tried to boot from my external DVD burner through USB cable and it wouldn't work. I read a thread which was posted a while ago regarding to USB boot on prior Intel Mac machines. But I have got the Intel C2D iMac so I don't why it wouldn't boot from USB. Could anyone give me some help on how to troubleshoot or fix the boot issue.

Thanks in advance :)

shihyuan
6th February 2009, 11:18 PM
Any advice from experienced mac users?

shihyuan
7th February 2009, 08:46 AM
Also if i have external HDD plugged in while booting up then do I suppose to see those drives in the boot menu?

Nexus
7th February 2009, 08:52 AM
Well if the external drive has a partition thats capable of booting. Then yes.

Otherwise, no.

shihyuan
24th February 2009, 12:02 PM
I tried everything that I could do possibly to figure out why i can't boot from my external DVD burner via USB. Could anyone else give some more suggestions?

MacDave
24th February 2009, 12:31 PM
I tried everything that I could do possibly to figure out why i can't boot from my external DVD burner via USB. Could anyone else give some more suggestions?

Not all external burners, USB or Firewire, can boot Macs. I suggest telling us the exact model of burner you have and researching on the web whether others have managed to boot from it.

Dave

shihyuan
24th February 2009, 01:05 PM
Not all external burners, USB or Firewire, can boot Macs. I suggest telling us the exact model of burner you have and researching on the web whether others have managed to boot from it.

Dave

It's a LG GH22NP20 22x DVD±RW DL IDE Drive. Click here (http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=370145597849) for more details for specifications.

It's USB external burner. I have the Intel iMac and I did the research and Intel iMac should be able to boot from USB drives if i am not mistaken.

mmulhern
24th February 2009, 01:46 PM
. . . . and the "bootable" media in the DVD drive is?

If the media is not bootable, then the drive won't show up in the boot list when you start your iMac (holding down the option key)

shihyuan
24th February 2009, 02:03 PM
. . . . and the "bootable" media in the DVD drive is?

If the media is not bootable, then the drive won't show up in the boot list when you start your iMac (holding down the option key)

Yes, the media is bootable........ It's a Windows XP SP3. I found this issue while I am trying to install boot camp on my iMac.

shihyuan
25th February 2009, 12:26 PM
I did more reseach in Google but still no luck. Could anyone suggest me the next step to solve the problem. :)

stewiesno1
25th February 2009, 01:58 PM
You do have it plugged into mains power too don't you ?
Another possibility is something that my mate experienced with his new Samsung SE-T084L which is a Lightscribe-enabled slot-loader. However, a feature which isn't given prominence is that it runs at half speed on USB power and full speed only when the supplied (very small) mains PSU is connected.

One other thing is that for some USB optical drives, sometimes the manufacturers make a big deal over the statement that the drive should only be used with the USB cable supplied.
Why ? I have no idea but I have seen it mentioned a couple of times.

From what I've read on PC sites the OS is supposed to identify the type of device on a USB port and, unless it requires higher power (500mA), the port is limited to low power (100mA).
If a drive doesn't identify as a high power device it only gets 100mA. I'm not sure why plugging a "power only" connector in helps. Perhaps it gets more because it doesn't identify.
Apple doesn't seem to follow the rules here. Although my M<S mouse gets 100mA and my Pro keyboard gets 250mA everything else gets the full 500mA.
Maybe your Win disc needs more oomph to run but Apple OS is letting the drive only get 250mA.

Stewie

shihyuan
25th February 2009, 06:09 PM
Maybe your Win disc needs more oomph to run but Apple OS is letting the drive only get 250mA.

Stewie

I am going to ask a very dumb question. How can I find out how much mA is OS giving to the drive and also how do I find out how much mA my external drive needs?

shihyuan
25th February 2009, 08:02 PM
Capacity: 623.5 MB
Removable Media: Yes
Detachable Drive: Yes
BSD Name: disk3
Product ID: 0x5621
Vendor ID: 0x0402 (ALi Corporation)
Version: 1.09
Speed: Up to 480 Mb/sec
Location ID: 0xfd100000
Current Available (mA): 500
Current Required (mA): 0
Mac OS 9 Drivers: No
Partition Map Type: Unknown
S.M.A.R.T. status: Not Supported

I checked and found that it says 0 mA required.... Is that normal?

stewiesno1
27th February 2009, 08:53 AM
Can you try and boot from an OSX disc on this drive ?

Stewie

shihyuan
2nd March 2009, 10:23 AM
Nope I couldn't because it doesn't recognise the drive before booting into OSX. Also one more thing that I found is while in OSX environment, if I tried to eject the drive by pressing the eject button, it wont eject the disc and there is no sign of power as well when i press the eject button but if i eject the disc from OSX then the drive will eject the disc..... I found this a very weird issue..


Can you try and boot from an OSX disc on this drive ?

Stewie

Lumus
2nd March 2009, 10:40 AM
Could it be that the Intel Mac's don't support booting from USB CD/DVD drives?

Read this (http://support.apple.com/kb/HT1948) as it explains


Intel-based Macs support starting from an external USB storage device's volume that:

* Has been formated with a GUID partition type
* Contains an installation of Mac OS X 10.4.5 or later, or Mac OS X 10.5 or later, which is compatible with (or shipped with) the Mac that the USB device is connected to. Note: You should not use a version of Mac OS X that is earlier ("older") than the version your Mac shipped with.

To start from a USB storage device that meets the above requirements, connect the device, then select it in Startup Disk preferences. Or, connect the device, restart, and immediately press and hold the Option key to access Startup Manager.

shihyuan
2nd March 2009, 10:46 AM
I did have a read at that page but I thought that only applies to booting from external HDD for Intel Macs. It mentioned nothing about booting from USB external CD/DVD drives. I have successfully boot from external CD/DVD drives on my previous Intel MBP.