Hi there, My daughter’s MBA 11” hard drive died recently. Rather than find another SSD card, is there a way I can buy a small USB drive, and have the OS X run permanently from it instead of an internal SDD? Thanks, Andrew
It’s certainly possible - I run and iMac and a Mac mini from USB drives (cheap way of getting SSD old-ish hardware)
In principle, it’s simple:
- Install Mac OS on a bootable USB. Google for instructions or there are a couple of free utilities to make it easier.
- Start the MBA from the USB stick and install/copy whatever you need.
- You can make the USB the default startup disk in System Preferences
I’m doing exactly this. My work machine is a mid-2012 13” MacBook Pro, and IT would prefer I not upgrade the OS.
So I installed the most recent Catalina beta (much more stable than earlier betas) to an external SSD, and I boot from that.
It works beautifully, and is tons faster than the internal spinning drive.
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PERFECT! I’m going to look into this my work work setup.
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In case anyone is curious: I’m using a 500GB Samsung T5. It frequently goes on sale for about $90. It seems to be a good drive, but there’s no need to pay full price under ordinary circumstances.
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Did you have to inform your IT dept of what you are doing or did you just go for it rogue-style? My dept here is pretty lenient, so I’m drafting up some ideas to present to them anyway
I tend to ask forgiveness rather than permission — but my IT department is used to me (I’m sure they roll their eyes, though). They are aware that I’m fine with being on my own, and that if I ever crash and burn, the only thing they should do for me is wipe and reimage the drive. If I lose data, that’s on me. 
Do be aware that there’s some new MDM stuff going on, so if your IT department does anything with managed devices and you’re connected to their network, you’ll trip something and they’ll know. I didn’t know that going in, so that’s how IT found out in my case (I was trying not to cause issues for them by booting from an external drive).
Thankfully, they’ve been okay with it.
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Sure, My husband has an old Mac laptop with dead internal drives but he boots multiple operating systems from thumb drives, usually various forms of Linux. I see no reason why you can’t do that with Mac OS. I ran it for quite a while off an external hard drive until I got a replacement.
Hmmmm. I’m wondering whether this option might offer a speed improvement on my iMac, which ideally I’ll hold onto a little longer - it’s late-2012, 2.9GHz, with only 8GB RAM.
Before I left it felt like it was struggling a little, but I’m not 100% sure exactly what limit I was hitting up against (RAM, CPU, etc)?
I’m on the opposite side of the world from it right now, but once I’m back is there any way to know whether running the OS from an external SSD would offer any improvements? I guess I could always just get one and test it out; then worst case scenario I have a drive on hand for backup etc…
I assume (without really knowing) that I am limited to a USB 2 connection if that makes a difference?
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I think you just have to try it to be honest
You should definitely try it - My iMac of similar vintage is noticeably faster (and quieter) since I started running it off a USB SSD.
Also worth considering - it’s quite cheap to get an internal SSD installed - it’s what we did for my partner’s older iMac and that runs a lot quicker
Meant to pop back in here much sooner to say: the external SSD has helped HEAPS. I can’t see myself replacing this computer anytime soon now. I hardly ever have to wait for anything now! So thank you all for your encouragement.
I have purchased a second one for my partners’ slightly-newer-but-still-struggling iMac as well.
(Tried it out on my old MacBook Air too but the effects were much less noticeable there. It’s older.)
Sort of / kind of a follow up. I have a 2TB Lacie drive connected via USB-C
Is there anyway to mark it as permanent storage so I can use it for OneDrive?
Thanks!
~Peter