Using Backup Copy of TimeMachine

NovaScotian · 02-27-2012, 05:18 PM

I have an underutilized but not really old HD for which I bought an external case. I'm in the process as I type this of backing up my TimeMachine disk for my iMac to it, but now wonder whether I'd actually be able to use it if my regular TM HD crapped out. Can TM be made to use an alternative HD?

NaOH · 02-27-2012, 05:43 PM

Quote:

Originally Posted by NovaScotian


	Can TM be made to use an alternative HD?

My memory is that I've seen a way to do that, perhaps with a third-party application or through some indirect method within Lion, but I can't track down what I (think I) saw. As a simpler approach, you may want to backup your primary Time Machine volume to the other drive. ganbustein explained a clever method for doing that in Post #10 of this thread.

NovaScotian · 02-27-2012, 05:50 PM

I read that, NaOH, but I don't want to move this HD to another machine; I want to be able to use it on this machine. What I've produced is a clone of my normal TM HD volume and I'm curious as to whether, should the original fail, I'd be able to convince TM to use the backup. Normally, if I swapped disks in the TM preferences, TM would overwrite what was there.

Hal Itosis · 02-28-2012, 01:35 AM

This might (or might not) be exactly what you're looking for:
http://hints.macworld.com/article.ph...71128055047339

in the event that it isn't, i'm almost certain that such a hint would exist somewhere on the main page. searching for 'time machine' produces more results than i care to sift through at the moment... but the link above appeared right away, so i posted it just in case.

ganbustein · 02-28-2012, 03:09 AM

Any Time Machine backup can be used to restore to the computer the backup was made for. When you do a full-disk recovery, you'll be asked:

Which disk do you want to restore to?
Which TM backup volume do you want to restore from?
Which snapshot on that volume do you want to restore?

If you're doing a partial recovery (just a few files/folders), you can tell TM to "Browse Other Backup Disks...". (It's in TM's dock menu. Or hold down the option key when you pull down the menulet from the menubar.) The "other backup" does not need to be of this computer.

Or, in TM's preference pane, use "Select Disk..." to make the other disk current (in which case it does need to be a backup from this computer). Then restore individual files/folders as usual.

If you're restoring to a computer different from the one you backed up from, full-disk restores are not reliable and not recommended. (The software you're restoring may not actually run on the new hardware.) However, Migration Assistant will accept a backup from a "foreign" computer, and handles any incompatibilities gracefully.

If you've made a clone of your TM backup, and the original backup dies (or even if it doesn't), use "Select Disk..." to choose the clone, and TM will happily adopt it, recognizing that what has already been copied doesn't need to be copied again. The clone should be made with SuperDuper, or by 10.6-or-later Finder. (CarbonCopyCloner will not correctly clone a TM backup, except maybe with a sector-level copy.)

The procedure Hal linked to is for the problem opposite to the one you're asking about: if the volume you're backing up from dies, how do you convince TM that the replacement disk is the "same" disk, so it doesn't back up the whole thing again? That procedure works only in 10.5. On Lion, there is a new command line utility (tmutil) that handles all that and more. In between, in Snow Leopard, Mandatory Access Controls rear their ugly head, and there's no easy workaround.

NovaScotian · 02-28-2012, 09:43 AM

Quote:

Originally Posted by ganbustein


	... If you've made a clone of your TM backup, and the original backup dies (or even if it doesn't), use "Select Disk..." to choose the clone, and TM will happily adopt it, recognizing that what has already been copied doesn't need to be copied again. The clone should be made with SuperDuper, or by 10.6-or-later Finder. (CarbonCopyCloner will not correctly clone a TM backup, except maybe with a sector-level copy.)...

Thank you for that ganbustein; that is precisely what I have done -- used SuperDuper! on a Lion machine to clone my normal TM volume to a backup volume. Glad to know it will be useful because it takes a long time to do.

Hal Itosis · 02-29-2012, 12:48 PM

?
10.7 - Using two Time Machine backups
?

NovaScotian · 02-29-2012, 01:05 PM

Glad to explore tmutil. Hadn't discovered it yet.

02-27-2012, 05:50 PM	#3
NovaScotian Hall of Famer Join Date: Oct 2002 Location: Halifax, Canada Posts: 4,945	I read that, NaOH, but I don't want to move this HD to another machine; I want to be able to use it on this machine. What I've produced is a clone of my normal TM HD volume and I'm curious as to whether, should the original fail, I'd be able to convince TM to use the backup. Normally, if I swapped disks in the TM preferences, TM would overwrite what was there. __________________ 17" MBP, OS X 10.8.3; 27" iMac, OS X 10.8.3

02-28-2012, 03:09 AM	#5
ganbustein MVP Join Date: Apr 2008 Location: Berkeley CA USA Posts: 1,009	Any Time Machine backup can be used to restore to the computer the backup was made for. When you do a full-disk recovery, you'll be asked: Which disk do you want to restore to? Which TM backup volume do you want to restore from? Which snapshot on that volume do you want to restore? If you're doing a partial recovery (just a few files/folders), you can tell TM to "Browse Other Backup Disks...". (It's in TM's dock menu. Or hold down the option key when you pull down the menulet from the menubar.) The "other backup" does not need to be of this computer. Or, in TM's preference pane, use "Select Disk..." to make the other disk current (in which case it does need to be a backup from this computer). Then restore individual files/folders as usual. If you're restoring to a computer different from the one you backed up from, full-disk restores are not reliable and not recommended. (The software you're restoring may not actually run on the new hardware.) However, Migration Assistant will accept a backup from a "foreign" computer, and handles any incompatibilities gracefully. If you've made a clone of your TM backup, and the original backup dies (or even if it doesn't), use "Select Disk..." to choose the clone, and TM will happily adopt it, recognizing that what has already been copied doesn't need to be copied again. The clone should be made with SuperDuper, or by 10.6-or-later Finder. (CarbonCopyCloner will not correctly clone a TM backup, except maybe with a sector-level copy.) The procedure Hal linked to is for the problem opposite to the one you're asking about: if the volume you're backing up from dies, how do you convince TM that the replacement disk is the "same" disk, so it doesn't back up the whole thing again? That procedure works only in 10.5. On Lion, there is a new command line utility (tmutil) that handles all that and more. In between, in Snow Leopard, Mandatory Access Controls rear their ugly head, and there's no easy workaround.

02-29-2012, 12:48 PM	#7
Hal Itosis Hall of Famer Join Date: Apr 2002 Posts: 3,315	? 10.7 - Using two Time Machine backups ? __________________ chown -R us /your\ base/ -HI- .

02-29-2012, 01:05 PM	#8
NovaScotian Hall of Famer Join Date: Oct 2002 Location: Halifax, Canada Posts: 4,945	Glad to explore tmutil. Hadn't discovered it yet. __________________ 17" MBP, OS X 10.8.3; 27" iMac, OS X 10.8.3

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02-27-2012, 05:18 PM	#1
NovaScotian Hall of Famer Join Date: Oct 2002 Location: Halifax, Canada Posts: 4,945	Using Backup Copy of TimeMachine I have an underutilized but not really old HD for which I bought an external case. I'm in the process as I type this of backing up my TimeMachine disk for my iMac to it, but now wonder whether I'd actually be able to use it if my regular TM HD crapped out. Can TM be made to use an alternative HD? __________________ 17" MBP, OS X 10.8.3; 27" iMac, OS X 10.8.3

02-28-2012, 01:35 AM	#4
Hal Itosis Hall of Famer Join Date: Apr 2002 Posts: 3,315	This might (or might not) be exactly what you're looking for: http://hints.macworld.com/article.ph...71128055047339 in the event that it isn't, i'm almost certain that such a hint would exist somewhere on the main page. searching for 'time machine' produces more results than i care to sift through at the moment... but the link above appeared right away, so i posted it just in case.