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[How to] Setting Your Partition "Active" Using Fdisk in MacOSX


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#21
speakerwizard

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Hi, thanks Rammjet but when i type "fdisk -e /dev/rdisk0" i get permission denied, do you know why this is? thanks in advance

#22
Rammjet

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Try "sudo fdisk -e /dev/rdisk0" and give your password when asked.

If you are actually booted from the install DVD as the guide says, it shouldn't need permissions.

#23
speakerwizard

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Hi Thank you soo much rammjet, it was booting from HD, but only with install disk in the drive, but that sudo thing worked a treat. Helpful guys like you are what make the net great!

#24
eyemac

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I tried cloning a disk with carboncopy cloner but when I then attempted to start from the cloned disk, it would not boot (got an error on verbose indicating still waiting for root). I assume this is because the disk is not set correctly. (MBR not set to active?) Is this correct? Can it be fixed with Fdisk as described previously by setting the partition to active? I would like to be able to clone an OSX86 disk so that I can upgrade to a larger capacity drive.. and I can do this with my PPC macs without problems. Thanks. SG

#25
Rammjet

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No, it's not a matter of setting the partition active.

If the clone is going to be the only thing on the drive, then the drive has to be prepared correctly.

http://forum.insanel...&...st&p=198548

#26
eyemac

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I checked your link.. it appears to relate to a fresh install. My take on it all is to follow the instructions up to the point of the install from the OSX86 install disk and then proceed to do the clone to the new disk. Is that correct?
I think my mistake was to repartition with the OSX Disk utility (?) rather than erase the partion and format it as a Mac partition.
Thanks
Steve

#27
Rammjet

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My take on it all is to follow the instructions up to the point of the install from the OSX86 install disk and then proceed to do the clone to the new disk. Is that correct?

Yes

I think my mistake was to repartition with the OSX Disk utility (?) rather than erase the partion and format it as a Mac partition.

The hard drive has to have an MBR partition scheme like a PC uses. Disk Utiliy on the install DVD is much older and cannot do that. However, the newer Disk Utility you get after an install can do an MBR partition scheme if you select the Option button to set it.

It is simpler to tell everyone to format the whole drive as FAT32 and then reformat the primary partition as HFS+.

#28
speakerwizard

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Hi, well i got it all up and running but now im just wondering about the updates, ive read a little (that i could find) but can anyone provide kind of a summery of how the update process works, i assume you have to wait for a mac/unix god to patch and release it, but are they whole, or in parts? do all parts generally work, or does it boil down to the system, what parts work and what ones dont?
thanks in advance guys (probably rammjet, im knew but he seems pretty helpful so far)

#29
tha_toadman

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good instructions. thanks for the info - wrote them on the back of my jewel case.

#30
Fidoboy

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I've followed the instructions and marked the HFS+ partition active, but it doesn't works. I have a external USB HDD width OS X 10.4.6 installed, this drive also have another partition in FAT32 format. I have Windows XP installed in my internal SATA HDD. If i boot from the install DVD and wait until countdown ends, i can boot into OS X, but if i try to boot from external USB HDD i only get a letter L at the bottom of screen and system hangs... ;)

Many thanks to all in advance,

.:FiDo:.

#31
jarodsix

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Now how about going into Start-> Control Panel -> Admin Tools -> Computer Management and in there on the left side select disk management (or what it is called) and a built in XP disk manager should appear. Now right-click the desired partition and "Make active". (this option shouldn't be greyed out even for OSX (AF) partition; wasn't for me).
Your machine will boot from OSX partition and you should be able to select which OS you want to boot upon OSX bootloader startup unless you have QuietBoot enabled with no Timeout key in com.apple.boot.plist - if so, you can hold F8 to bring up the OS selector.

#32
cjnucette

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Thanks Rammjet, this solved my problem, but when it boots it says :
"The CPU has been disabled by the guest operating system. You will need to power off or reset the virtual machine at this point.".

Anyone can help me.

My Specs:
Mobo: Intel D946GZis
CPU: Pentium D 3.40GHz
RAM: 1GB DDR2
HD: 160GB SATA, 80GB IDE (Installed here)
Video: PowerColor Radeon X800 GT
Sound: SoundBlaster Audigy

#33
bombice

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worked great thanks!

#34
tomkiwi

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Hey Rammjet ,
I get an error "fdisk is in the form dev/rdisk0"

when i type fdisk -e/dev/rdisk0
or fdisk -e /dev/rdisk0

Any suggestions?
I've had this working before (to set my other OS active, i used the same commands from the same OSX dvd yet it isn't working this time.

Thanks in advance,
Tom

#35
Rammjet

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I get an error "fdisk is in the form dev/rdisk0"

when i type fdisk -e/dev/rdisk0 <-- incorrect
or fdisk -e /dev/rdisk0 <-- correct

Any suggestions?

See comments in quote above.

Be sure you type a zero instead of the letter "O"

Also, be sure you are pointing to the correct hard drive. If OSX is on a partition on the 2nd hard drive then the command uses: rdisk1

#36
Sondless

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now when i restart, nothing happens. no b0 error or anything. I still need the install dvd to do it

#37
Dolphininblue

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Hi,

Do I still need to make the partition active only if Mac OS X is the only OS on my machine?


Please help.




There are a lot of people who experience a b0 error on their first boot up after installation. Or the bootloader immediately takes them back to the Windows installation (on dual boot).

These people probably forgot to set the MacOSX partition "Active"

A common mantra provided here to newbies for setting up for installation is:

  • Make the partition Primary
  • Make the partition ID=AF (signifies an HFS partition)
  • Make the partition Active
There is a built-in Unix utility in MacOSX that can be used to set your partition "Active". It is called Fdisk
Setting Your Partition "Active" Using Fdisk

Words in bold below are things you must type (followed by Enter).

1. Boot your Mac OS X install dvd
2. Once the installer is running, go to the Utilities menu and open Terminal

3. Determine which disk your MacOSX partition is on


Type diskutil list

Verify which disk number holds your partition (disk0, disk1, etc.)


4. Start using Fdisk


Assuming the MacOSX disk is the first disk ("disk0"), then
type fdisk -e /dev/rdisk0 <== use "rdisk" with your disk number here !!

Ignore the error "fdisk: could not open MBR file ..."


5. Determine which partition for MacOSX needs to be set "Active"


Type p

Verify which partition is for MacOSX (1, 2, 3, etc.)


6. Set the partition "Active"

Assuming it is partition 1, then
type f 1 <== use your partition number here !!


7. Save and exit


Type write

Type y (yes you are sure)

Type exit (to quit)


8. Remove the install DVD and reboot



#38
BOBSONATOR

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Hey, guys, i did the command

fdisk -e /dev/rdisk0

Then

Flag 1

now there is a * next to my first partition,

so i save,

then exit

then it reboots,

and i see the ATI Mobility 9000 vesa... so and so,

then a bunch of text goes flying past my screen for like 10 secs saying loading so and so,

then i see a blank screen,

then it restarts itself.

Thanks for help/

#39
Rammjet

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Setting the partition active got your computer to boot the OSX partition. The errors have to do with your OSX installation. Start a new thread for your booting/restarting problem. It is no longer an issue of setting your partition active.

#40
Lowcash

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There are a lot of people who experience a b0 error on their first boot up after installation. Or the bootloader immediately takes them back to the Windows installation (on dual boot).

These people probably forgot to set the MacOSX partition "Active"

A common mantra provided here to newbies for setting up for installation is:

  • Make the partition Primary
  • Make the partition ID=AF (signifies an HFS partition)
  • Make the partition Active
There is a built-in Unix utility in MacOSX that can be used to set your partition "Active". It is called Fdisk
Setting Your Partition "Active" Using Fdisk

Words in bold below are things you must type (followed by Enter).

1. Boot your Mac OS X install dvd
2. Once the installer is running, go to the Utilities menu and open Terminal

3. Determine which disk your MacOSX partition is on


Type diskutil list

Verify which disk number holds your partition (disk0, disk1, etc.)


4. Start using Fdisk


Assuming the MacOSX disk is the first disk ("disk0"), then
type fdisk -e /dev/rdisk0 <== use "rdisk" with your disk number here !!

Ignore the error "fdisk: could not open MBR file ..."


5. Determine which partition for MacOSX needs to be set "Active"


Type p

Verify which partition is for MacOSX (1, 2, 3, etc.)


6. Set the partition "Active"

Assuming it is partition 1, then
type f 1 <== use your partition number here !!


7. Save and exit


Type write

Type y (yes you are sure)

Type exit (to quit)


8. Remove the install DVD and reboot


thanks for the great advice and help Rammjet. I have a quick question. i did as you said and now i just sit a a blinking cursor. i made the 0 my active partition. could i have made the wrong one active? how can i tell which one should be active? kind of new at this





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