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Using OS X on External Drive to Boot Two Different Macs?

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MacCast    80

I had someone ask me recently about this and I was wondering if anyone here had any experience doing this. Basically they want to install OS X Lion on an external volume and use it as the boot OS drive for two different Macs (one at home and one at work). In theory I would think this would work just fine, but the question is are there any unforeseen issues in doing this? The two I can think of are:

  1. Differences in hardware, specifically OS X firmware that might be specific to one model vs. the other
  2. Hardware drivers. Similar to item #1. If there are default drives needed for one Mac that were;t installed because the OS was tailored for the other Mac.

Hope this makes sense.

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johnfoster    48

OS X is a uni-driver system. when installing on a Mac it doesn't do an install based on specific hardware.

 

the issue is going to be the overall speed of the system which will feel very sluggish because of the slow old ports. USB2 has a MAX datarate of 480 megabits a second. compared to SATA or SATA two which has a speed of 1.5 gigabits a second and 3 gigabits a second respectively. but bus speed isn't the entire story. USB is heavily reliant on the CPU instead of having the heavy lifting done in hardware like FireWire. this is the other reason why a USB boot feels like a slug.

 

FireWire might be a better option. keep in mind that a FireWire 800 drive case costs around $100 and up because there is zip for demand.

 

the best solution would be to use an eSATA case for the hard drive. but sadly Macs do not have an eSATA ports. wait… none of them do. while most Windows machines have eSATA.

 

the better solution would be to have a MacBook Pro that you carry around. or even better, when you go home STOP WORKING!

Edited by johnfoster

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MacCast    80

Thanks John. One of the machines involved is actually a new Retina Macbook Pro, but sounds like there isn't a BYOD policy at his work, so the stop working thing may be the only option.

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Huskermn    33

Maybe, the real question is - why does the person want to do that? Maybe, thee's a better solution to the problem than botting two machines from one drive to have the two machines be 'the same'/in sync.

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johnfoster    48

the first course of action would be to ask "work" what they would suggest. there may be issues with compliance for software, data, or other policy that needs to be covered. thing is as long as it's the work box then it's somebody's jorb to deal with. but once it's some hybrid thing that some employee has done then it's banana land.

 

always ask.

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macboer    1

Why aren't you guys answering the question? I guess no one here has tried it before.

 

Anywho, I'm not the biggest geek around but I can't see why this won't work. It's at least worth a shot.

 

Having said that, I do agree with the others that this should not be the first option, as FW might not be as fast as the person would like/are used to.

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johnfoster    48

okay. I thought I was specific. my answer should have implied that it would work. so yes. you can boot two different Macs from the same hard drive (but not at the same time.) I've done this on several occasions.

 

1) used an 1st gen iPod to boot my demo environment. it had all my installed apps, demo files and we used it to play tunes on the way to the event.

 

2) I keep a hard drive loaded with an OS X installer and the common apps that need to be installed afterward so I can upgrade a Mac anywhere. the hard drive install is about 4X faster compared to the same install from a DVD.

 

3) another old drive is loaded with 10.X so it can boot. on that disk are some trouble shooting tools to check SMART, recover files (Data Rescue to the rescue) and other tools. usually it's too late to help because the borked drive is tick tick ticking.

 

4) OS X 10.8 is installed on a external drive so that the office can stay complient with the NDA that Apple requires. instead of putting a Mac away when "clients" come by it is shut down and the drive is put away in a cabinent.

 

5) booting from external drive makes for a slow Mac experience. it works but it's not the same speed as a internal hard drive. you will rethink this madness after the 18th beach ball.

 

6) seriously, if you job requires you to work 25 hours a day get another Mac, sync your work files with DropBox or RSYNC. or make work buy you the second Mac because over it's life time it will save them thousands more than it actually costs. and if they don't they are being cheap bastards. also, if IT doesn't know how to poke a hole in the router to allow RSYNC to work then figure out how to make it work with a thumb drive.

 

TLDR booting from a hard drive on two different Macs works. you just won't like the experience.

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Rogier    3

Models build after "Early 2010" don't have a Universal build.

This is because the Apple has started to use different Intel chipsets for the processor and graphics.

During the installation the specific drivers are automatically installed and the OS X configured for that particular hardware configuration ("build").

Therefor you cannot boot reliable from an external drive from an other machine if this machine is a different "build" then the one used to create the boot drive.

 

Worse case you will get a instant kernel panic or at best various issues and stalls...

 

Hope this helps,

 

Rogier

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Graham    1

I'm sorry, but thats wrong. I use the same 10.7.4 image on every mac I come across (except the latest mid 2012 laptops, which I expect will be merged into the main OS branch in 10.7.5). Apart from a few random byhosts preferences, you'll be fine. If you can get a thunderbolt external, you might not even notice the difference. I wouldn't do this (I use a combination of dropbox and git to keep my machines in sync). but it would work if one of the newest machines wasn't involved.

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