dual-bootpartitionssdunix
Currently I am running only Ubuntu on my MacBook Air. Many have suggested I reinstall or install macOS on an external drive in case I ever need to troubleshoot, or in case something goes wrong. How can I install macOS on an external SSD from Ubuntu itself? Is this possible or do I need to use a friend's Mac?
In case Ubuntu didn't start up or break for whatever reason, would it be as simple as plugging in the SSD with the macOS and then pressing Option (Or optionally Alt) to boot from the SSD?
Turns out resetting PRAM and NVRAM via pressing ⌘+⌥+P+R at boot (before the gray screen appears; hold until computer restarts and the startup chime has been heard twice) fixes the problem.
I have since successfully booted both OSX and Ubuntu via rEFInd without any excessive waiting.
Update 3:
There were a two reasons I wanted the output from diskutil and fdisk. First I wanted to check if rEFIt was installed on its own partition. It is not. This leaves either the EFI partition or the OS X partition. The normal (automatic) installation would be OS X, which is backed up with Time Machine. To be safe, you could backup the EFI partition. This is not a problem since it is only 210 MB in size. I usually just make an exact image copy of the entire partition. The command is shown below. The image file efi.img will be stored in the root directory of the OS X partition.
sudo dd if=/dev/disk0s1 of=/efi.img bs=10000
I do not know if Time machine will backup the "Recovery HD" partition. It is only 650 MB in size. Again, you can just image it to the root of OS X using the command below. My outline did not include migrating this partition to the new disk. Therefore, you probably will never use this file.
sudo dd if=/dev/disk0s3 of=/RecoveryHD.img bs=10000
The second reason, for running the diskutil and fdisk commands, was to determine if you are using a GPT or hybrid GPT/MBR partitioning scheme. You are using hybrid GPT/MBR. I assume then that Windows is using the legacy BIOS method of booting and not using the EFI to boot.
According to your original post, you intend to upgrade to Yosemite after migrating to the new drive. It just so happens, I am trying to help someone (riznad) who has already done this. See here. Upgrading to Yosemite disabled rEFId and created a new "Recovery HD" partition. So you may need to reinstall rEFId. I would not recommend upgrading to rEFInd.
I am not sure why you felt the need to use the rEFId boot manager. I use the System Preferences in OS X to boot to windows. Apple provides Boot Camp to boot from Windows back to OS X. On startup, you can hold the alt key to choose an operating system. I rarely need to do that. In riznad's case, rEFId makes sense, that computer has a third partition running the Fedora operating system.
If you wish to have a partition writeable by both OS X and Windows, now would be a good time to create it. This can be done by creating the partitions in the following order using the Disk Utility. First create the MS-DOS(FAT) partition for windows 7. This partition will be changed to NTFS by Winclone. Format the next partition as MS-DOS(FAT) or ExFat. Finally, put the OS X partition last.
Update 2:
Just FYI, the output of chkdsk can be viewed in the Event Viewer. An example is shown below. You can "Open Image in a New Window" to enlarge.
An example output is shown below.
Checking file system on C:
The type of the file system is NTFS.
Volume label is Orca.
One of your disks needs to be checked for consistency. You
may cancel the disk check, but it is strongly recommended
that you continue.
Windows will now check the disk.
CHKDSK is verifying files (stage 1 of 3)...
123136 file records processed.
File verification completed.
171 large file records processed.
0 bad file records processed.
2 EA records processed.
50 reparse records processed.
CHKDSK is verifying indexes (stage 2 of 3)...
168030 index entries processed.
Index verification completed.
0 unindexed files scanned.
0 unindexed files recovered.
CHKDSK is verifying security descriptors (stage 3 of 3)...
123136 file SDs/SIDs processed.
Cleaning up 12 unused index entries from index $SII of file 0x9.
Cleaning up 12 unused index entries from index $SDH of file 0x9.
Cleaning up 12 unused security descriptors.
Security descriptor verification completed.
22448 data files processed.
CHKDSK is verifying Usn Journal...
36677272 USN bytes processed.
Usn Journal verification completed.
Windows has checked the file system and found no problems.
107460604 KB total disk space.
30413860 KB in 94522 files.
64108 KB in 22449 indexes.
0 KB in bad sectors.
228944 KB in use by the system.
65536 KB occupied by the log file.
76658804 KB available on disk.
4096 bytes in each allocation unit.
26865151 total allocation units on disk.
19164701 allocation units available on disk.
Internal Info:
00 e1 01 00 e3 c8 01 00 a5 53 03 00 00 00 00 00 .........S......
bf 03 00 00 32 00 00 00 00 00 00 00 00 00 00 00 ....2...........
11 00 00 00 00 00 00 00 03 00 00 00 00 00 00 00 ................
Windows has finished checking your disk.
Please wait while your computer restarts.
What you are looking for is the messages Windows has checked the file system and found no problems. and 0 KB in bad sectors.
Update 1:
It is my understanding rEFIt installs in the OS X partition. According to the rEFIt documentation, it is also possible for rEFIt to be installed on a separate partition or on the hidden EFI partition. No mention of being installed on the Windows partition.
Assuming rEFIt was installed using the automatic installation, then it should be saved by Winclone followed by Time Machine. But to be honest, I have never used rEFIt.
To be safe, it would be useful for you to post the output from the following commands. They can be entered from a Terminal application window. The first one will ask for your login password. This is normal.
sudo fdisk /dev/disk0
diskutil list
diskutil cs list
Other than Winclone creating a backup of Windows on you OS X partition, the procedure does not change the files on your original disk. If you wish, you can also backup Windows to a external disk that is HFS formatted (Mac OS Extended Journaled). This way Windows does not have to pass through Time Machine.
I don't know where you are living. Where I live, I would go to Microcenter and buy an enclosure for the new disk. I would then plug the enclosed drive into a USB port on the Mac. Transfer everything over. I would also boot OS X on the the enclosed drive and test things out. From my understanding, you can not boot windows. You might be able to from Parallels. I have never used Parallels. I would then remove the drive and return the enclosure for a full refund. (Actually, have done this a few times with 3.5" drives.) The drive could then be installed in the MacBook Pro.
If you proceed, it would be a good idea to run CHKDSK on the windows partition before backing up with Winclone. CHKDSK (Check Disk) has be around since the original IBM PC-DOS 1.0. The best way to do this is to open a Command Prompt window as an Administrator under Windows 7 and enter the command:
fsutil dirty set c:
After entering the command, reboot (restart) Windows. It usually is not necessary to see the results, but if you wish, I will post how to do so using the event viewer. (You can also watch the screen during boot up)
I can outline the basic steps using the Winclone product.
If you wish to proceed, let me know. Also, if klanomath happens to post, I would recommend any of his solutions. He has more experience with Time Machine than I have.
Best Answer
It is quite simple to install macOS on an external drive using macOS Internet Recovery.
Plug in the external drive.
Turn on or restart your Mac, then immediately hold down ⌘ + R keys.
Release the keys when you see the Apple logo or a spinning globe.
macOS Utilities window similar to the one below will be displayed.
Proceed to erasing the external disk by selecting Disk Utility and clicking continue.
Select your device or volume in the sidebar of Disk Utility.
Click the Erase button or tab.
Complete these fields:
Name: Enter a name for your disk, such as "Macintosh HD".
Format: Choose Mac OS Extended (Journaled) or APFS.
Scheme (if available): Choose GUID Partition Map.
Click Erase to begin erasing your disk.
When done, quit Disk Utility to return to the utilities window. You're now ready to install macOS.
Choose Reinstall macOS (or Reinstall OS X) from the utilities window.
Click Continue, then follow the onscreen instructions. You'll be asked to select your disk. Select the external disk (identify it with the value supplied for Name in step # 8).
Click Install. Your MacBook Air will restart after the installation is complete.
Voila! Your bootable external disk is now ready.
Yes, if you are unable to boot into Ubuntu for whatever reason, you can simply plug in the external SSD with the macOS installed and then press and hold Option (Alt) to boot from the external SSD?
To boot from the external disk:
Turn on or restart your MacBook Air with the external disk connected.
Press and hold the Option key immediately.
Release the Option key when you see the Startup Manager window.
Select your startup disk, then click the arrow under its icon, or press Return.