Long-term running of Mac on external hard drive

[nathansmart]

My hard drive on my iMac just died and I know you can boot from a bootable external hard drive but how long can you do that?

I plan to get a new internal drive but I don't have the money right now and I have some amply-sized external drives that I can boot from if I want to. "Logic" says there's no issue doing it (it's just a hard drive on the outside) but my "logic" isn't as strong when it comes to this kind of thing so I was wondering if everything would work the same or if something wouldn't work if the drive is on the "outside?"

 

[nambuccaheadsau]

Well I did it with an external TB SSD for speed on a 2011 iMac for a couple of years no problems. Just make sure you had been cloning the internal to the external and it was selected to be bootable. Into System Preferences and with the external connected, select (highlight) as the boot drive.

 

[Guy Clark]

My hard drive on my iMac just died and I know you can boot from a bootable external hard drive but how long can you do that?

I plan to get a new internal drive but I don't have the money right now and I have some amply-sized external drives that I can boot from if I want to. "Logic" says there's no issue doing it (it's just a hard drive on the outside) but my "logic" isn't as strong when it comes to this kind of thing so I was wondering if everything would work the same or if something wouldn't work if the drive is on the "outside?"

Absolutely fine and for some the preferred method for running macOS particularly if the internal drive is a 5400rpm HDD. Although USB 3.0 is acceptable the external drive preferably should be hooked up to the Thunderbolt port for maximum performance.

 

[nambuccaheadsau]

I use two Kingston Now SSDs for backing up externally. One via USB3 and the other by TB. Guess what? Using SuperDuper to do Smart Backup one after the other, task completed within one second of each other so not much real world difference. USB3 much cheaper.

 

[Guy Clark]

I use two Kingston Now SSDs for backing up externally. One via USB3 and the other by TB. Guess what? Using SuperDuper to do Smart Backup one after the other, task completed within one second of each other so not much real world difference. USB3 much cheaper.

Thunderbolt 2 is four times faster than USB 3.0 however Thunderbolt 2 is more expensive. If you were to run an SSD on an external USB 3.0 there would be a significant bottleneck where the SSD would be only as fast as the speed of USB 3.0 therefore there would be little to gain running SSD through USB 3.0 More suitable would be a High Performance HDD such as the Western Digital Black
http://www.itpro.co.uk/storage/22740/usb-vs-thunderbolt-which-is-better
https://www.wdc.com/products/internal-storage/wd-black-mobile.html

 

[J.Gallardo]

You are mixing things... Disk interface is the “thing”: you can expect same speed with an external ssd with SATA interface, connected to usb or Thunderbolt ports. Bottleneck is SATA.
There are pure Thunderbolt disks, but they’re quite expensive right now. Also, you can get a real Thunderbolt external case (expensive) and plug a PCI ssd blade (expensive) to achieve max. speed.

Anyhow, answering OP: you can work with confidence running on ext. disk. Perhaps some issue with sleep-wake function... but I doubt it.
In fact, if my internal disk would fail (out of warranty), I would consider this solution less risky than a repair...

 

[Fishrrman]

The OP asked:
"My hard drive on my iMac just died and I know you can boot from a bootable external hard drive but how long can you do that?"

In January, 2013 I bought a late-2012 Mac Mini.
From the moment I took it out of the box, I connected it to an SSD in a USB/SATA dock and booted and ran it that way.
It ran great.

Today, almost six years later, it's still booting and running from a USB/SATA dock.
And it still runs great. Typing on it now.

Is that "long enough" for ya...?

In another reply above, it was stated that thunderbolt was "faster than" USB.
It's worth mentioning that some years' back, the barefeets site tested a thunderbolt enclosure SSD vis-a-vis the same SSD in a USB3 enclosure.
The USB enclosure won.

Get something like a Samsung t5 USB3 drive.
Plug it in and set it up to be the boot drive.
I predict that you'll become a very VERY happy user.

 

[BigMcGuire]

The OP asked:
"My hard drive on my iMac just died and I know you can boot from a bootable external hard drive but how long can you do that?"

In January, 2013 I bought a late-2012 Mac Mini.
From the moment I took it out of the box, I connected it to an SSD in a USB/SATA dock and booted and ran it that way.
It ran great.

Today, almost six years later, it's still booting and running from a USB/SATA dock.
And it still runs great. Typing on it now.

Is that "long enough" for ya...?

In another reply above, it was stated that thunderbolt was "faster than" USB.
It's worth mentioning that some years' back, the barefeets site tested a thunderbolt enclosure SSD vis-a-vis the same SSD in a USB3 enclosure.
The USB enclosure won.

Get something like a Samsung t5 USB3 drive.
Plug it in and set it up to be the boot drive.
I predict that you'll become a very VERY happy user.

Im another user just like Fishrrman. I’ve been running my Mac mini via external drive for three years with a Samsung Evo 850 usb 3.0.

 

[BlueTide]

I did this for years with a work laptop. I had an external drive to boot from to use as my personal machine at home. It worked better when the laptop was docked (duh), but it wasn't too bad on the move either when suction cupped to the lid.

 

[nathansmart]

Thanks everyone!!