Home Forums Mac Software Mac Operating Systems Useful tip...

I'm surprised that nobody's linked to this yet...

How to create an OS X installer from Apple's Internet Recovery

I'll guess that this will be a machine specific installer.

It can be done even more easily with Apple's "Recovery Disk Assistant" utility.

Start the app from your Desktop, pop in a USB drive and the rest happens automatically.

Two observations: you really must use a USB drive of some sort, even the small flash versions. You cannot use an SDHC flash card. Second, once the Installer has been made, it will not appear on the Desktop (although Disk Utility will see it). Like the above linked article says, once you start in Recovery Mode, the flash drive will appear as an installation option.

Thanks for mentioning that much easier method; it's more surprising that Kessler forgot about it than it is that I did.

Edit: You obviously had me convinced for a moment, but I did some reading and re-reading, and I see that you're incorrect...


RDA replicates, on a flash drive, HD functionality that merely enables you to d/l OS X, while the posted methodology creates an actual installer.

It's unnecessary if you purchased OS X from the App Store, but not if you got it pre-installed on a new Mac.

Apologies to Kessler.

It's the other way around. It's unnecessary if you got it installed on a new Mac, because any such machine will also have Internet Recovery in ROM.

You need Recovery Disk Assistant if you do not have Internet Recovery in ROM, and want to guard against the possibility of losing your Recovery HD, perhaps because of having to replace the drive. (Internet Recovery just downloads a copy of the guts of Recovery HD, and boots from it.)

Note that Time Machine also puts a copy of (the guts of) Recovery HD on the backup disk. (At least, it does so on 10.7.2 and later, if the backup disk is directly attached. I'm not sure what it does when backing up to Time Capsule or a network-connected disk.)

Recovery HD, no matter how you get to it, only lets you download the installer. It does not contain the actual installer. The only way to spare yourself the download is to save the installer itself to something bootable. (Or do a full restore from TM rather than a system re-install.)

"The only way to spare yourself the download is to save the installer itself to something bootable. (Or do a full restore from TM rather than a system re-install.)"

Just to clarify--are you saying that a restore from a Time Machine backup can reinstall the System?

I have done restores using Migration Assistant and a Time Machine backup and have only seen user data. This actually makes sense from a "migration" standpoint. What's the mechanism for a System reinstallation from a TM backup?

Boot into Recovery HD or it's equivalent. (If you hold down the option key at startup, a local TM backup will show up as an option. Selecting it uses the copy of Recovery HD that TM put on the volume.)

Choose "Restore from Backup", then follow the delightfully clear instructions for how to do that. (Select the backup volume to use, select the particular snapshot you want to restore, select the disk volume you want to restore it onto.) You're doing a full disk restore, so it will end up being exactly like it was when you made the snapshot. That includes whatever version of the OS was on that volume when you backed it up.

I've experimented with this procedure to get answers to the obvious questions:

• Yes, you can restore to a prior version of the OS. (I tested going back to Snow Leopard.) You restore to the exact version of the OS that was on the backup.
• No, you do not need an internet connection. (I've done this with my DSL modem turned off, just to verify.)
• Restoring to Lion or later will re-create the Recovery HD partition. (The first step in restoring is to erase the volume you're restoring onto. Erasing a volume merges it with its companion Recovery HD partition, but restoring Lion or later puts it back.)

TM has always, even on Leopard when it was brand new, been able to restore to a previous (or future) version of the OS. You do, of course, need to be backing up system files, but it's foolish not to. I always make sure I have a current TM backup before running Software Update, so I can back out an update I don't like. (I've never had to, but it's comforting to have the option.)

To back out a software update without losing any of your own work, do a full disk restore from before the update, followed by a normal restore of just your home folder from a later snapshot. It's a poor excuse for a time machine that can only travel through time in one direction.

My statement that you quoted did not apply to RDA, so even though your response is factually correct, it is incorrect as respects my post.

The tip that launched this thread is directed towards users who acquired OS X pre-installed on new Macs and wish to create bootable installers to take on the road.

It's an adaptation of the widely known procedure for creating a bootable installer from an App Store d/l, which procedure is not available to the users it addresses.

Therefore, as I said, "It's (The tip's) unnecessary if you purchased OS X from the App Store, but not if you got it pre-installed on a new Mac."

I would also point out this method has one other useful advantage. It will NOT perform an internet verification of eligibility when booting off that image.

Also, if you do this trick with the retail downloaded installer (from a machine you have upgraded to) it will be a universal image and not machine specific image.

What is an "an internet verification of eligibility?"

> Also, if you do this trick with the retail downloaded installer (from a machine you have upgraded to) it will be a universal image and not machine specific image.

Thanks for mentioning that; I've been wondering whether OS X purchases from the App Store were universal or machine specific.