Swapping HDDs w/ Different OSX Versions, Possible

efihard drivekernel

My situation: I have a "late '08 aluminum" Intel 64-bit MacBook, still have Snow Leopard installed, and XP via Bootcamp, all on the original hard-drive. Yes, it's my "legacy" setup. The HD is 7 years old, and every time I move the computer and the HD makes that clicking "disengage" sound for impact protection, I cringe a little bit.

What I want to do: I want to put in a new Intel SSD with the latest OS (Mavericks, Capitan, heck even Mountain Lion, whatever will work in my situation), and put the old HDD in a drawer. I want the ability to swap in my old HDD to use Snow Leopard/XP without any difficulties. I don't want to jeopardize backwards-compatibility with Snow Leopard at the bootloader or EFI level. I am worried that Mavericks, Capitan, etc. will go all crazy and re-wire the whole EFI, because Snow Leopard was the last version to use a 32-bit kernel, even though my Mac has a 64-bit Intel processor. (Source)

Extra info: I have never turned on FileVault, Time Machine, or signed in with an Apple ID on the current installation, but plan to use Apple ID on the new one. — Model Identifier: MacBook5,1 — Boot ROM Version: MB51.007D.B03 — SMC Version (system): 1.32f8

What I have questions about:

Which OSX version, if any, can I upgrade to without jeopardizing my old setup? So if I swapped in my old hard-drive, Snow Leopard and XP will boot as if nothing happened?
Once EFI firmware is updated to work with the latest OSX, is it backwards compatible with older versions by means of swapping in an old HD? I also know OSX has some form of Keychain security, but is it used in the booting process? I will use the same local username/password.
Does signing in with Apple ID on Mavericks/Capitan/Yosemite lock the EFI to that specific OS installation? Like an anti-theft kind of deal? I know Apple is big about security…

Thanks in advance for any expert advice in this situation!

Best Answer

Since I am currently using a 20-inch, Mid 2007 iMac, I am somewhat familiar with upgrades. When I installed Snow Leopard, it ran as a 64 bit operating system. I have installed every version of OS X since Snow Leopard without any problems. I am currently running both Yosemite and El Capitan. I have run Vista 32 bit, Windows 7, 8, 8.1 and 10 64 bit, even though Apple only officially supports up to Windows 7 32 bit on my iMac.

According to the site: OS X El Capitan - Technical Specifications, you can run El Capitan on your Mac. I assume then, you could also install an older version of OS X. Of course, finding one to download might be a problem.

Your question:

Which OSX version, if any, can I upgrade to without jeopardizing my old setup? So if I swapped in my old hard-drive, Snow Leopard will be accessible and boot as if nothing happened?

Any OS X newer that Snow Leopard. You could even move your Snow Leopard to the new SSD and install another OS X version.

Your question

Once EFI firmware is updated to work with the latest OSX, is it backwards compatible with older versions by means of swapping in an old HD? I also know OSX has some form of Keychain security, but is it used in the booting process? I will use the same local username/password.

People often return you computer's OS X to factory conditions. Whether this means using a DVD that came with your Mac or downloading from the internet, I do not think any Firmware upgrade would disable your ability to do this. In other words, Firmware upgrades should not prevent Snow Leopard from running on your Mac.

Your question:

Does signing in with Apple ID on Mavericks/Capitan/Yosemite lock the EFI to that specific OS installation? Like an anti-theft kind of deal? I know Apple is big about security...

No. I currently have two versions of OS X installed. Your Apple ID has nothing to do with the EFI.

Related Solutions

MacOS – Where is the EFI stored on the macbook and is it possible to restore a previous EFI firmware version

If you can successfully start your Mac from a Mac OS X DVD take a look at this: http://pubmem.wordpress.com/2011/04/09/flash-efi-firmware-update-manually-on-a-macbook-51/, especially comment 54 and follow-ups.

It explains how to manually flash the EFI firmware:

Download the EFI Firmware update from Apple. This link lists EFI and SMC firmware updates. You will need the exact model identifier of your Mac.
Unpack the firmware pkg using unpkg. You will need access to a Mac for this, as unpkg only runs on OS X. You need the file with extension scap.
Start your Mac from a DVD and select Utilities>Terminal.

Now comes the difficult part. You need to run this:
```
sudo bless -mount / -firmware /path/to/your/firmware.scap
```
It is unclear to me whether / is the right path (as asked in comment 59) or if you can even access the internal harddisk when booting from a DVD. You may have to plug in an external drive and copy the scap file there... You will have to figure it out for yourself.

Alternatively, you can try:
```
sudo bless -device /dev/disk1 -firmware /path/to/your/firmware.scap
```
Restart. The Mac should flash the EFI firmware.

Disclaimer: Be aware that I couldn't test any of this so I'm giving the following information as a hint in the hope that it is useful.

Installing Snow Leopard on external drive with newer iMac version

Both Macs support 10.6.6 (the MacBook Pro probably was delivered with a Snow Leopard 10.6.6 DVD) as well as any later system up to at least 10.10 and both contain a DVD-drive. The MacBook Pro's optical drive seems to be damaged or malfunctioning.

Without manipulating the innards of Mavericks you usually can't install an older system over a newer system even if you install it to another volume. To circumvent this restriction use another method:

Here is a straightforward guide how to clone the Snow Leopard DVD to a thumb drive, then boot a second Mac from the thumb drive and install the OS. You can use a modified guide to accomplish the same on your iMac without needing to manipulate your Mavericks system.

Format the external drive:

Open Disk Utility and format the external drive.
Click the Partition tab
Under the Partition Layout header click on the 2 Partition option in the drop-down menu. One big partition and a second smaller one with at least 8 GB at the end. Use the options button to choose GUID partition table.
Click the Format drop-down menu and select Mac OS Extended (Journaled).
To format the external drive finally, click the Apply button in the lower right-hand corner of the Disk Utility window.

Restore the Snow Leopard DVD or a Disk Image:

Locate a Snow Leopard disk image or DVD on the Mac
If you're using a disk image, mount it to the desktop
In the Disk Utility window, click the Restore tab in the external's drive's menu

In the center of the window you'll see two boxes: one labeled Source and another Destination.

Drag-and-drop the second partition of the external drive into the Destination box
Drag-and-drop the Mac OS X Install Drive disk into the Source box
At the bottom right-hand corner of the screen and click the Restore button

Disk Utility will restore the OS X Install DVD or disk image to the external drive; this process may take anywhere from 20 minutes to an hour depending on how quick the Mac is.

After the process has finished quit Disk Utility and try to reboot the iMac to the external disk. If the reboot is successful disassemble the external drive and move the disk to the MacBook Pro.

Boot the MacBook Pro to the second partition and install Snow Leopard to the first partition of your MacBook Pro disk.

After installing and rebooting to the first partition, open Disk Utility remove the second partition and expand the first partition to the full size.

If you have a spare thumb drive with at least 8 GB you may use this one instead and follow the guide in the link.

Best Answer

Related Solutions

MacOS – Where is the EFI stored on the macbook and is it possible to restore a previous EFI firmware version

Installing Snow Leopard on external drive with newer iMac version

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