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OSX wont boot from external USB HD


alexp
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alexp, the mac os x kernel doesn't know about the BIOSes ability too Boot USB drives, it tries to boot off ATA/SCSI until it dies. I did encounter this problem myself while trying to install from an USB DVD drive.

 

Fortunately, you can probably get this solved.

 

You have to set your root device manually, eiter at boot time or in com.apple.Boot.plist:

 

1. Find out the drive and partition number where your installation resides Numbering scheme ist simple, diskNsM where N is the n-th hard drive beginning at 0, while M indicates the partition number (the first partition is 1). So if you have one internal drive and installed on first partition on USB drive it should be disk2s1

2. At boot prompt, type root=disk2s1 -v (see above!)

3. if it doesn't work, repeat from 1.

4. if it works, edit com.apple.Boot.plist

 

Don't expect too much performance from Mac OS X while running from USB! Concurrent reads ad writes un USB HDDs are f***ing sloooow.

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alexp, the mac os x kernel doesn't know about the BIOSes ability too Boot USB drives, it tries to boot off ATA/SCSI until it dies. I did encounter this problem myself while trying to install from an USB DVD drive.

 

Fortunately, you can probably get this solved.

 

You have to set your root device manually, eiter at boot time or in com.apple.Boot.plist:

 

1. Find out the drive and partition number where your installation resides Numbering scheme ist simple, diskNsM where N is the n-th hard drive beginning at 0, while M indicates the partition number (the first partition is 1). So if you have one internal drive and installed on first partition on USB drive it should be disk2s1

2. At boot prompt, type root=disk2s1 -v (see above!)

3. if it doesn't work, repeat from 1.

4. if it works, edit com.apple.Boot.plist

 

Don't expect too much performance from Mac OS X while running from USB! Concurrent reads ad writes un USB HDDs are f***ing sloooow.

 

Ok! I'll try, but first of all I need to install OSX, because I formatted the drive..

Is it possible, using your method, to install osx directly on the external HD?

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Is it possible, using your method, to install osx directly on the external HD?

 

Should work. The Installer has no problems with USB, and JaS' DVD did boot very well in my USB DVD drive (with root=disk1s3 given).

However, newer OSx86 versions show some weird behaviour when Booting off USB. Sometimes I had to unplug/plug the drive in order to boot properly. Just give it a try and let us know wether it works.

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Ok, I tried, but with no success!

The disk utility doesn't recognize the external HD..I tried also to unplug & replug it, but the installer crashed!!

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alexp, the mac os x kernel doesn't know about the BIOSes ability too Boot USB drives, it tries to boot off ATA/SCSI until it dies. I did encounter this problem myself while trying to install from an USB DVD drive.

 

Fortunately, you can probably get this solved.

 

You have to set your root device manually, eiter at boot time or in com.apple.Boot.plist:

 

1. Find out the drive and partition number where your installation resides Numbering scheme ist simple, diskNsM where N is the n-th hard drive beginning at 0, while M indicates the partition number (the first partition is 1). So if you have one internal drive and installed on first partition on USB drive it should be disk2s1

2. At boot prompt, type root=disk2s1 -v (see above!)

3. if it doesn't work, repeat from 1.

4. if it works, edit com.apple.Boot.plist

 

Don't expect too much performance from Mac OS X while running from USB! Concurrent reads ad writes un USB HDDs are f***ing sloooow.

 

Tried this, with "disk3s1" that is my external HD, but it still doesn't work!

 

always the same...STILL WAITING FOR ROOT DEVICE :wacko::rolleyes:

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