Why won't my iMac boot from an external drive?

I have an external drive that has a clone of my other iMac running Mountain Lion made with Super Duper which boots up fine with the machine it's a clone of but will not boot on my new iMac running Yosemite or my MacBook running Snow Leopard. I want to upgrade the OS on this drive to Yosemite so that I can transfer files and applications to my new machine without overwriting the newer versions of Apps I already have on it. I can select it as the Startup Disk but when it tries to boot I get the No Entry sign and it halts. Any ideas? I could do the upgrade on my old iMac but I have a very slow broadband connection and it will take hours to download, blocking use of the machine which my wife needs to have access to, hence the convoluted process.

It won't boot from the new iMac because it's older than the OS that came with the new one. I'm not sure that a laptop will boot from the clone of a desktop.
Use setup assistant to migrate just your files from the old computer. If you already passed up using setup assistant, then you can use migration assistant to transfer your files.
If you don't want to use the above, put the computers on the network and enable file sharing. Log onto the old computer and copy whatever you want to transfer to the user desktop of the new computer. This will change the permissions of those files to the new system. Then you can log onto the new iMac and move those files where you want them.

Similar Messages

Can my iMac boot from an external drive?

Once upon a time, I used Disk Utility, running from the DVD to make a copy of my iMac's internal drive. I also tried using Carbon Copy Cloner to do the same thing. But, I have never been able to get the iMac to recognize the external drive as a boot drive. I just wanted to have a backup that would launch when the internal drive tanks... as it will, one day.

Yes. If you did it right then to boot from the clone:
Boot Using OPTION key:
1. Restart the computer.
2. Immediately after the chime press and hold down the
      "OPTION" key.
3. Release the key when the boot manager appears.
4. Select the clone's disk icon.
5. Click the arrow button on the far right.
To make the clone:
Repair the Hard Drive and Permissions
Boot from your Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the installer.
If DU reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
Clone using Restore Option of Disk Utility
1. Open Disk Utility in the Utilities folder.
2. Select the destination volume from the left side list.
3. Click on the Restore tab in the DU main window.
4. Select the destination volume from the left side list and drag
       it to the Destination entry field.
5. Select the source volume from the left side list and drag it to
      the Source entry field.
6. Double-check you got it right, then click on the Restore button.
Destination means the external backup drive. Source means the internal startup drive.

Why won't my Mac boot from a Firewire drive?

Hi all,
I have a 500GB Internal Western Digital hard drive from inside my Mac Pro that I'd like to use to boot my 24" iMac. The drive is running 10.7.2 Server and I've confirmed that it is using GUID (in Disk Utility).
I'm using my Newer Technology Voyager dock over Firewire to connect the internal drive to the iMac. I get the same results over FW 400 and 800.
If I boot the iMac using it's internal drive running 10.5.8, the external drive in the NT dock mounts fine in the Finder. I then open System Preferences > Startup Disk and select the external drive. When I click restart, the iMac boots right back to its internal drive. When I boot the iMac holding the option key, only the internal drive appears.
Suggestions? Thanks

I do not have an answer, but perhaps some experiments.
Can you put the Mac Pro into Firewire Target mode, and have the iMac see the Mac Pro via Firewire? Target mode is done by booting the Mac Pro while holding down Command-T. This might confirm that your iMac will boot via Firewire, and that maybe it is an issue with the Newer Tech. At best it is a way to isolate one component.
Do you have another drive you can experiment with? Just about any size would do. Put it in the Newer Tech dock, then try installing any version of Mac OS X via the iMac. Does that boot the iMac?

Booting from an external drive when the internal has died

Hello, I have an older iMac mid 2007 2.4 GHz Intel model. Around 2009 my internal hard drive failed and for the last few years I had a nice work around using an external drive to boot into OSX. I was curious however if anyone knew of an official or well documented method of using this method because for what ever reason the drive is not being recognized. My method is a combination of trial and error until it booted properly but recently it has just stopped recognizing the disc or when installing the OS it will just fail near the end of the install. Tried to hold Option with the disc installed on boot to see if I could boot from CD but it never seems to show up as an option.
I thought that the drive was damaged but I was able to reformat and use it for a few months with my PC so I have confidence it is not that.
The other problem I was curious about is the format of the drive and how I can even go about reformatting to the mac journal. I cant seem to get into disk utility all I get is a white screen.
Any help is greatly appreciated.
Original Information
OS: 10.4.x
Ram: 2g ddr2
I have been able to many time before reinstall using my leopard and snow leopard disks.

Okay just clarifying my INTERNAL hard drive is most likely dead, I am looking to install and boot from my external hard drive. According to this AHT article
Before you begin
Important: If your Mac was released after June 2013, you will use Apple Diagnostics rather than Apple Hardware Test (AHT). See Using Apple Diagnostics for instructions.
Consider doing some preliminary troubleshooting to determine if your issue is related to hardware. You can try to determine if the cause of your issue is related to hardware or software by following Isolating issues in Mac OS X. AHT can help determine which hardware component may be causing the issue.
Before starting AHT, be sure to disconnect all external devices except the keyboard, mouse, display, and Ethernet adapter. Also disconnect any external optical drives.
My goal is to find a way to boot from my external drive.
"Won't matter, as long as you have the Disc.
To make it botable, you will need to set the Partition Map Scheme (GUID Partition Table) and Format it (Mac OS Extended Journaled) before installing OS X."
The disc or the drive? I assume you mean the drive but according to the document that should be removed.

Can I boot from an external drive with a "Virtual CD"

I just purchased a Hitachi LifeStudio external hard drive for use as my Time Machine backup. When I plugged it in to my MacBook running 10.6.4, I realized that it had one of those "Virtual CDs" that contained the manufacturers crapware, similar to Western Digital's MyWare or whatever its called. It shows up in disk utility as an actual separate disk and not just another partition that can be wiped.
I reformatted the drive using GUID and and created 3 HFS+ Journaled partitions. One was going to be for the 10.6 installer, one for the 10.6 boot, and one for my time machine backup. I restored a 10.6 install dvd disk image I created using disk utility to the 10.6 installer partition (with erase destination checked) then option booted my mac and the partitions did not show up. The only thing I could see was my internal hard drive.
I have done this many times before and it has always worked so Im trying to figure out what Im doing wrong. The only thing I can think of is that the "Virtual CD" that Hitachi put on this external drive is stopping the Mac from seeing the bootable partitions I created. I even went into system preferences>startup disk and blessed the 10.6 install partition. That didn't work either, the computer just booted to my internal drive.
So my questions are. Is it because of this "Virtual CD" that I can't boot from my external drive? If so, is there a way around it? I already searched their web site and emailed their tech support asking for a firmware update to remove the virtual cd.
Thanks in advance.

Yes, it's a known issue. You've already referred to the issue with WD systems. WD has a long list of products that are either not compatible with Macs or won't boot a Mac.
There are practically no problems with bare drives, but once installed in an enclosure there is no guarantee that the package will function as a bootable device. This is especially the case if the manufacturer uses some sort of "virtual" scheme intended for using the device as a sort of one button backup device.
External drives don't have to specifically say anything about being Mac bootable or compatible. It's up to the consumer to verify compatibility and usability.

OSX 10.4 not booting from an external drive..

I have an 1 Ghz G4 iMac that is causing some major headaches.
It started by the machine crashing every 15-20 minutes.
A fresh re-install seemed to be the best option.
In order to sort out the problem I decided to install a fresh copy of OSX on an external firewire drive.
The install went without any problems but then I was unable to boot from the firewire drive.
Even holding down the option key and selecting the drive manually didn't do anything.
I then decided to do an archive install on the internal drive. This crashed in mid-installation making the internal drive in-accessible.
Anybody have any tips on how to get out of this mess?
E.

Since your machine crashed while running from the install disc, it sounds like there is a problem not related to the Operating System on your drive. Have you installed any ram, other than that which came with your iMac? If so, remove it and try to boot from your firewire drive again. (The installation onto that drive was sucessful, right?)If you're successful in booting the computer and it runs with more stablility minus any extra ram, you have a bad ram stick.
My fear here is that since your previous re-install failed I'm not certain that another attempt to install on that drive wil save all your stuff... if you can boot from your external drive, I'd rescue your data, photos, music, etc., to the external before trying to re-install on your internal drive.
Dual 1.8 G5, Powerbook G4 1.5GHz Mac OS X (10.4.8)

Booting from an external drive 10.3.2 with new i7 mac mini

How to boot from an external drive with 10.3.2 using a new i7 mac mini. Seems to be a build problem?

Your Mac is incapable of running 10.3.2. The version of OS X 10.3 is PowerPC only and your Mac has an Intel processor.
Why do you want to do that?
Allan

Will Mac allow you to boot from an external drive...specifically for windows programs?

Will a new Mac allow you to boot from an external drive...specifically for windows programs?

ps...I've read the threads on Bootcamp.

Booting From An External Drive in OS 9.2?

I have a G4 with a bad internal ROM drive. I am currently running OS 9.2.
I would like to upgrade to OS 10.
I have an Iomega USB 2.0 external drive connected to my computer via the USB port in the back.
How can I boot from the disk in this external drive?
I tried holding "option"- it only found my regular hard drive.
I tried holding "cmd-opt-shift-del" but my mac got very confused and blinked a ? at me.
How can I boot from the external drive so I can upgrade?
Thanks
O.

Welcome to Apple Discussions!
Mac OS X will not boot from USB drives on a PowerPC.
You need a Firewire optical drive to boot, and an AGP PowerMac G4 at that to boot Mac OS X. To identify your PowerMac G4, see this article:
http://docs.info.apple.com/article.html?artnum=58418
Once you've identified it, boot the machine into Mac OS 9 on the hard drive and make sure your firmware is up to date:
http://docs.info.apple.com/article.html?artnum=86117
And then you'll be able to install Mac OS X. Follow these precautions on my FAQ before doing so:
http://www.macmaps.com/upgradefaq.html
If it turns out you have a PCI PowerMac G4, you'll have to replace the optical drive internally to boot Mac OS X or Mac OS 9.
Also make sure your clock battery is under 4 years old before attempting to upgrade the firmware. It is a 3.6 V 1/2 AA battery you can buy from Radio Shack item 23-026.

How Do I Always Boot From An External Drive

I successfully installed Mac OS X 10.4.8 on an external hard drive. It boots successfully into OS X, but only if you press option on boot and select the drive or if you boot from the drive inside my Mac Mini and go to startup disk and select the external. Is there any way to just always boot from the external drive without doing anything? Thanks in advance for all of your help.
Mac Mini PowerPC Mac OS X (10.4.8)

If booting from a cold start doesn't work but restarting after selecting the drive does work, then most likely the drive isn't ready when the Mac is doing the cold boot.
Try turning the drive on several seconds before turning on the Mac.

How do I boot from an external drive?

I've just Carbon Cloned my 60GB drive to a firewire external drive. I'm about to replace the 60GB with a 160GB drive and the CCC instructions say boot from the external drive I'd just created once the new disk is installed. Then CCC the cloned drive back to the new hard drive.
So, how do I boot from an external drive? Do I have load anything to the new drive? Will the macbook detect the external drive and boot from that? Or what??????
Thanks
Dick

Thanks DWB. Being the rash impetuous guy I am I didn't wait for replies and just switched on the macbook after installing the new disk (which was so easy it was unbelievable - had to go and buy a a little torx bit though) to see what would happen.
Blow me down with a feather if it didn't just boot off the external drive all by itself :-O It did come up with the disk was unverified and I could see it in FINDER and I was prseented with a screen to ERASE/RESTORE etc.
When I went to CCC the external drive back to the new hard drive it didn't give show me the new hard drive so I guessed I'd have to do something to format (?) the hard drive.
I don't know if I did the right thing but I went to disk utilities and chose ERASE in the vague hope it would maybe format the disk in some way.
Seems to work now and the CCC replaced the system perfectly as far as I can see.
Basically very impressive all round. Piece of proverbial to replace the disk and CCC made life so easy.
Thanks again.
Cheers
Dick

Mac Mini i7 (Mavericks) will not boot from the external drive

Mac Mini i7 (Mavericks) will not boot from the external drive with Disk Warroir 4.4. or Drive Genius or Lion.
Not even from the external Firewire hard drive with Mavericks

Does the external HD have a GUID partition table?
Is the external drive formatted Mac OS X Extended (journaled)?
Is this a 2011 or late 2012 Mac?
How was Mavericks installed on the external drive?
Who is the builder of the drive mechanism in the external drive?
Who is the builder of the external enclosure?
What type of interface does the external drive have USB2, USB3, Firewire 400, Firewire 800, thunderbolt?
Is the external enclosure directly connected to the mini?
Have youtried a different interface cable?

Elitebook 8440p - recovery disc creation & booting from an external drive

I have a brand new Elitebook 8440p & I have a couple of issues that I cannot seem to resolve.
1. I expected to get some sort of system install, or recovery or repair discs - or the ability to create such disks with this laptop. Nothing came with it, and I cannot find any place to create some sort of system recovery disks, nor is there anything listed for this laptop on the HP site to acquire them from HP. I am not comfortable having no way to recover this computer should a hard disk go south. Any ideas how to create or get an op system disk or recovery discs or something?
2. I have an encrypted company/business hard disc inside the laptop for work. I also have the original hard disk that came with the computer in an external eSata/USB case. I have configured and installed software on the external drive to include my personal software and programs, leaving the company hard disc inside the laptop for business use only. However, I cannot make this laptop boot from the external drive if the company drive is inside the laptop. I have read and tried everything, but if a drive is inside the laptop, it will not boot from the external eSata/USB drive. If I simply remove the laptop hard drive, it boots perfectly from the external drive via eSata and works fine. How do I manage to get this laptop to boot from my external drive without having to remove the internal hard drive?
Any help or ideas someone can offer are greatly appreciated. Thanks very much.

Hi, Rich:
If you live in the USA or Canada, you can get a set of restore disks from HP for $10. I am surprised you didn't get a set but maybe they only come with the business desktops.
Here is how you order them:
1. Write down the part number and serial # on bottom of the computer on the white tag. The model # is an HP-Compaq 8440p, but the part number will be found on that white tag below the serial #.
2. Call HP at 1-800-952-7689, option 1 (ordering restore disks is part of the list in the option).
3. Provide the info asked by the rep that answers the phone. Some just ask for the serial #, some want both, or they will just want the serial number and type of computer (8440p).
4. Have a Master Card or Visa ready for purchasing. They don't take Discover. You will be charged $10.00.
You will receive the disks by First Class Mail or you can pay an additional $10.00 for FedEx shipping.
Sorry, I can't answer your second question. I assume you have already tried hitting the F9 key at the HP splash screen to select the device to boot from?
Paul

FV2 and booting from an external drive

Hi,
When Lion came out I decided to enable filevault as I take my laptop everywhere.
Periodically I take a full SuperDuper backup of my hard drive just in case the worst happens.
I have read that its best to remove the FileVault protection before entertaining an upgrade so I have removed FV and took another full superduper backup.
Part of my upgrade plan is to test the backup by booting my MBP from the external drive so that I know I can get back to my old machine but I am finding that I can reboot my MBP and select the backup drive from the bootable selection and I get the apple logo and the spinning cog but it doesnt go any further.
I think this has happened since enabling FV as I have never had an issue before booting from an external drive.
I have formatted the drive and started a fresh SuperDuper backup and this hasnt made a difference either.
Any help would be appreciated.
Thanks
Gavin

They all are formatted Extended and with Guid partition map. So I am good that way. I will have to experiment I suppose. Thanks for your response.

Is there a way to boot up an iMac G5 from an external drive (PowerBook G4) running 10.2.8?

I have an iMac G5 running 10.5.8 and a couple of MacBooks running 10.6.
I also have a cherished old PowerBook G4, which will only rarely and briefly start up these days. It runs 10.2.8.
I would like to try to recover the original working environment (files and OS but also user interface, desktop settings, preferences, etc) of the PowerBook G4. I presume that one way of doing this would be to remove the hard drive of the PowerBook, place it in an enclosure, and try to boot up from it as from an external hard drive.
Would this be possible? Would I be able to boot my iMac G5 from the old drive or would this be impossible because of the drive's 10.2.8 OS? What are the alternatives?
What are some tips for doing this sort of thing safely, to begin with?
Any thoughts much appreciated!

Instead of booting from the external, which as Niel pointed out, is not possible, how about simply dragging the data you need from the external after you mount it?

Why won't my iMac boot from an external drive?

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