Booting Up from another Hard Drive


macrumors newbie
Original poster
Mar 25, 2016
Hi all,

Hoping you can offer some help. I've tried searching the forums but can't find something exactly like my issue.

I have a Macbook Air which I bought to replace a Macbook 13.3". I have kept the hard drive from the Macbook and I would like to access it with my MacBook Air. There's photos and videos on this hard drive I'd like to access. I'd like to keep the information on the external hard drive as it has a lot of stuff on it and I don't want to fill up my MacBook Air.

I'm guessing I'll need to select a different boot up drive but I'm not too technically confident so would like to get some advice from someone who is.




macrumors 601
Apr 19, 2017
Toronto, Ontario, Canada
If you put the old hard drive into an external enclosure, boot the air as you normally would and connect the external drive via USB and copy, view, delete files via finder.


macrumors newbie
Apr 29, 2014
As Audit13 said. Your stuff will be in the Users folder. But it is possible some files might be unaccessible that way, encrypted, inaccessible when not signed in. If that's the case you should be able to hold the Option key to boot with the old hard drive in the enclosure to get access to and copy over anything you couldn't access when in the new Air.

IF you have a lot of space on the old drive, AND you manage to get "copies" of all the crucial stuff just incase of error, you might want to ADD a partition to the old drive using Disk Utility when booted into the new Air. (Not repartition, but the Plus button to ADD to the old one. That way you split the old drive into 1) your original Mac system there, plus 2) a drive you can use for storage, or even as a time machine for your new drive. And, that way you can use the old system as an emergency boot up drive in case something goes wrong on the Air.


macrumors 6502a
Aug 8, 2016
The old system could theoretically have installed Mac OS X Snow Leopard on it, that is unlikely to boot with a new Mac Book Air unless it's a 2010 or earlier model. Is there a problem to use it as an external drive, like @Audit13 suggested?


macrumors G3
Jul 30, 2003
Another possibility, if the old hard drive was the boot drive for the MacBook, and has the old OS X system.
You COULD simply update the system on that hard drive, using a system version that WILL boot on your newer MBAir.
That probably would assure that you can access everything on that drive, while you are booted to it --- and, using the same apps, with the same desktop background, dock icons, everything would be the same.
And, nothing on the old hard drive would affect the MBAir storage in any noticeable way. Everything would remain on the old hard drive :D


macrumors newbie
Apr 29, 2014
Ya, I was thinking like DeltaMac too that it might be worth updating the system on the old drive. So you could have it as a working system if you need it. But only as a backup boot system really, since the MacBook air local system will be faster. Personally I like to keep my backup boot drive very empty, and with a different desktop so that I know I am only using it temporarily. Anyway, to respond to main question, ya sure you can use any external drive just to access files, as long as you can read and write to everything.

To keep things simple though, you might just want to transfer files off it while you have space the Air, erase it completely, then transfer back. Of course then you don't end up with an emergency boot drive, but to contradict myself, it is pretty rare, well never really, that I have needed a backup boot drive. ;-)