Difference between Restoring From Time Machine Backup and Clean Install + TM Restore

ducatiti

macrumors 6502a
Original poster
May 18, 2011
932
153
I apologize if this has been discussed before but I could not find the answer.

When you boot up from an OSX install disk, you will have an option of "reinstall OSX" or "Restore from Time Machine Backup". So what is the difference of restoring from Time Machine on that menu from a clean install and a manual time machine restore.

I have always done a clean install followed by a time machine restore. I was wondering if I can do that in one step as mentioned above.
 

T5BRICK

macrumors G3
Aug 3, 2006
8,095
2,057
Oregon
I apologize if this has been discussed before but I could not find the answer.

When you boot up from an OSX install disk, you will have an option of "reinstall OSX" or "Restore from Time Machine Backup". So what is the difference of restoring from Time Machine on that menu from a clean install and a manual time machine restore.

I have always done a clean install followed by a time machine restore. I was wondering if I can do that in one step as mentioned above.
When you do a clean instal and a manual time machine restore, you have the option of migrating certain types of user data. I don't believe you have this option when restoring from a backup.
 

gentlefury

macrumors 68030
Jul 21, 2011
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0
Los Angeles, CA
When you do a clean instal and a manual time machine restore, you have the option of migrating certain types of user data. I don't believe you have this option when restoring from a backup.
Yes, this is good if you are restoring to a smaller drive. It lets you restore what you want do you can restore the system without apps, which can save a lot of room.
 

JTToft

macrumors 68040
Apr 27, 2010
3,405
754
Aarhus, Denmark
Simply put, the difference is that with a clean install + TM you get the clean installation plus your data from TM, whereas with a full TM restore, the operating system is restored from the TM drive as well.

If your Time Machine backup has the newest version of OS X and you are restoring to the same hardware, there is absolutely nothing wrong with doing a full Time Machine restore.
 

gentlefury

macrumors 68030
Jul 21, 2011
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0
Los Angeles, CA
Simply put, the difference is that with a clean install + TM you get the clean installation plus your data from TM, whereas with a full TM restore, the operating system is restored from the TM drive as well.

If your Time Machine backup has the newest version of OS X and you are restoring to the same hardware, there is absolutely nothing wrong with doing a full Time Machine restore.
Yes, this as well. Tho because of this fact the time machine restore is WAY faster. Clean install has taken me upwards of 3 hours if their servers are jammed, since you have to download the installer before it can do anything. Whereas time machine restore takes about 35 mins.
 

JTToft

macrumors 68040
Apr 27, 2010
3,405
754
Aarhus, Denmark
time machine restore takes about 35 mins.
- While your statement that a Time Machine restore will probably be faster than a clean install (if you count the download time as part of the install) is correct, it just needs to be added that how long a Time Machine restore takes depends entirely on how much data you need to restore. :)
I think it took about 1 hour for me when I installed Mountain Lion. I did a fresh install and restored my data from Time Machine afterwards.
 

gentlefury

macrumors 68030
Jul 21, 2011
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Los Angeles, CA
- While your statement that a Time Machine restore will probably be faster than a clean install (if you count the download time as part of the install) is correct, it just needs to be added that how long a Time Machine restore takes depends entirely on how much data you need to restore. :)
I think it took about 1 hour for me when I installed Mountain Lion. I did a fresh install and restored my data from Time Machine afterwards.
Of course I count download time. I have a very fast connection and should be able to download the 4GB install image in about 30 mins or so....but it took several hours to install because of the seriously slow download time on Apples part.
 

ducatiti

macrumors 6502a
Original poster
May 18, 2011
932
153
- While your statement that a Time Machine restore will probably be faster than a clean install (if you count the download time as part of the install) is correct, it just needs to be added that how long a Time Machine restore takes depends entirely on how much data you need to restore. :)
I think it took about 1 hour for me when I installed Mountain Lion. I did a fresh install and restored my data from Time Machine afterwards.
.

Why are you guys using Internet recovery instead of installing ML off a USB stick?

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Simply put, the difference is that with a clean install + TM you get the clean installation plus your data from TM, whereas with a full TM restore, the operating system is restored from the TM drive as well.

If your Time Machine backup has the newest version of OS X and you are restoring to the same hardware, there is absolutely nothing wrong with doing a full Time Machine restore.
So you are saying that a full TM restore will restore OSX from the TM backup? I don't think that TM backs up the operating system. Other opinions would be appreciated. I could be wrong though.
 
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iAppl3Fan

macrumors 6502a
Sep 8, 2011
789
19
What they are saying makes sense. I typically just do a clean install and manually pull data from the time capsule without the migration assistant.
 

shigatashway

macrumors member
Aug 29, 2011
92
14
It should be noted that (unless things have changed under ML) if you do a time machine restore, the recovery partition is not installed onto your hard drive. Always seemed strange that it wasn't designed to take that into account under Lion.
 

JTToft

macrumors 68040
Apr 27, 2010
3,405
754
Aarhus, Denmark
.

Why are you guys using Internet recovery instead of installing ML off a USB stick?
- Where did you get that idea? I installed Mountain Lion from an SD card, not through Internet Recovery.

So you are saying that a full TM restore will restore OSX from the TM backup? I don't think that TM backs up the operating system. Other opinions would be appreciated. I could be wrong though.
- Yes, it will. And yes, it does back up the operating system. See for yourself: If you look at the total used space on your main hard drive partition, unless you have excluded something from Time Machine, it should match the estimated size of a complete Time Machine backup (you can find this under Time Machine's settings). This means that Time Machine includes all data on the partition it was set to backup.