Is it possible to cleaninstall and reinstall OS X with a USB boot ?

Pandarama

macrumors member
Original poster
Jun 1, 2015
56
4
France
Hello,

I use to cleaninstall and reinstall OS X with a USB key, and boot on USB. It is possible with an adapter and a classic USB key ?

Thanks a lot
 

tutux

macrumors member
May 4, 2015
80
7
What would be the advantage compared to an install via the system recovery (and do a clean install from there)?
 

Pandarama

macrumors member
Original poster
Jun 1, 2015
56
4
France
I'm not sure but I think :
First you win some time, because you have already DL the OS (from Mac App Store, but you can work/chill during), you only have to install it.

Then it's more proper than a wifi install.

I prefer boot on USB than recovery system, I have an USB key dedicated to do that.
 

tutux

macrumors member
May 4, 2015
80
7
I'm not sure but I think :
First you win some time, because you have already DL the OS (from Mac App Store, but you can work/chill during), you only have to install it.

Then it's more proper than a wifi install.

I prefer boot on USB than recovery system, I have an USB key dedicated to do that.

The only technical valid point here is that you don't have to DL the entire OS (I tend to forgot this point because I have fast internet access).

Then, if you prefer to do it this way, it's like I prefer to drink my coffee without sugar, matter of taste, and will not argue this :)
 

Pandarama

macrumors member
Original poster
Jun 1, 2015
56
4
France
The only technical valid point here is that you don't have to DL the entire OS (I tend to forgot this point because I have fast internet access).

Then, if you prefer to do it this way, it's like I prefer to drink my coffee without sugar, matter of taste, and will not argue this :)
Exactly, I prefer, but if u have stable and fast access it's the same :) (but there is a rumor that says from USB is more proper than wifi)

The question is : How long does it take from USB boot ?
 

tutux

macrumors member
May 4, 2015
80
7
Exactly, I prefer, but if u have stable and fast access it's the same :) (but there is a rumor that says from USB is more proper than wifi)
Curious to read details as download from internet basically download the dmg+ scripts to do exactly the same as usb key but from recovery partition...

Urban legend I guess?
 

Pandarama

macrumors member
Original poster
Jun 1, 2015
56
4
France
Curious to read details as download from internet basically download the dmg+ scripts to do exactly the same as usb key but from recovery partition...

Urban legend I guess?
Yes urban legend for sure ;)
 

darngooddesign

macrumors G3
Jul 4, 2007
9,343
264
Atlanta, GA
Exactly, I prefer, but if u have stable and fast access it's the same :) (but there is a rumor that says from USB is more proper than wifi)

The question is : How long does it take from USB boot ?
I don't have an answer to your question, but I would like to point out that installing from the recovery partition is not the same as internet recovery. The OS installer is on your harddrive already so it would actually be faster than booting from external USB.
 

bcaslis

macrumors 68020
Mar 11, 2008
2,167
200
Yes, I've done it.

Download the Yosemite installer. If done now, it will be 10.10.3 which is the minimum version you need. Let it download but quit the installer when it starts to run. Use a formatted USB stick at least 8GB minimum. Then run these commands in the terminal window:

sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction

Note this assumes the USB stick is named Untitled. This will take about 20 minutes. When complete restart and hold the option key. Select the USB stick as the startup. Then after the you boot to the installation window, select Disk Utility from the menubar at the top. You can then then format or erase the SSD. Then quit Disk Utility and run the installer on your cleaned out SSD.

I do this for almost all new Macs and I get and I did this for the rMB.
 
Last edited:
  • Like
Reactions: theSeb
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.