5 ms·

I've booted my iMac from an external thunderbolt SSD for years. Once you set it to boot from an external SSD, it will happily continue doing so. Much faster th

by jamesu 8y ago

I've booted my iMac from an external thunderbolt SSD for years. Once you set it to boot from an external SSD, it will happily continue doing so. Much faster than the real slow hdd it came with at least, plus I don't have to open it up to clear out the data when I'm finally done with it. I still have yet to figure out how to create a similar hassle-free "live" booting environment which works across various hardware for windows and linux.

stcredzero 8y ago
Once you set it to boot from an external SSD, it will happily continue doing so. What happens when the soldered-on SSD fails? Can you alter a setting in the PRAM or SMC to let the system completely disregard the failed SSD?
- rangibaby 8y ago
  It remembers which drive it boots from so as long as you keep the external drive connected it should boot from it
  - bitL 8y ago
    Still, another dongle to carry (with Mac Mini it's not that important) and a loss of speed/added latency for e.g. video editing. With normal usage patterns even USB 3.0 external thumb/SSD drives were just fine.
    - stephenr 8y ago
      So use a tb3 enclosure with an nvme inside.
      - Sephr 8y ago
        There are no bus-powered TB3 M.2 PCIe enclosures, and there never will be any[1]. This means you will have to buy a huge bulky externally-powered TB3 PCIe dock costing hundreds of dollars to accomplish this. 1. https://twitter.com/sephr/status/817883011165233152?s=19 https://twitter.com/sephr/status/817883011165233152?s=19
        stephenr 8y ago
        No, it says there won’t be any that are sold unbundled.
    - rsync 8y ago
      "Still, another dongle to carry (with Mac Mini it's not that important) and a loss of speed/added latency for e.g. video editing. With normal usage patterns even USB 3.0 external thumb/SSD drives were just fine." What is the speed difference between the on-board PCIe connected SSD vs. the USB3 connected SSD ? Aren't both PCIe and USB3 faster than the SSD, making it the bottleneck ? A flash drive would, of course, be terribly slow ... do they make USB "thumb drives" that are SSD (not flash) ?
- shaggerty 8y ago
  Yes, if the soldered-on SSD has failed you can boot from an external drive by holding down the alt/option key while the system powers on to bring up the boot selection menu.
  - Wowfunhappy 8y ago
    I thought this no longer works with the T2 chip? Don't you run into issues with e.g. upgrading the firmware because it will only accept firmware updates from the internal drive?
    - Foivos 8y ago
      I got a brand new mac with a T2 chip this week from my work. The first thing I did was do all the updates, including a security update for the OS, which required a restart. During the restart it was giving errors, so it was not able to boot properly. It would just give the error message and you could only restart again, just to have the same thing happen. A colleague more familiar with macs, brought up a menu, where you could choose which drive to boot from, which eventually fixed the problem, since it booted from the hard disk. In my case this menu had only the internal ssd, since I did not have anything else connected. I would guess that if I had an external hard drive it would show up as well. Also on the documentation of the T2 chip, Apple strongly recommends to use file vault, because if you do not, the ssd even though it is encrypted by default, gets decrypted [1] upon being mounted. To sum up, I guess it is possible to boot from whatever device you want. [1] https://support.apple.com/en-us/HT208344 https://support.apple.com/en-us/HT208344

by jamesu 8y ago

stcredzero 8y ago

Once you set it to boot from an external SSD, it will happily continue doing so. What happens when the soldered-on SSD fails? Can you alter a setting in the PRAM or SMC to let the system completely disregard the failed SSD?

rangibaby 8y ago
It remembers which drive it boots from so as long as you keep the external drive connected it should boot from it
- bitL 8y ago
  Still, another dongle to carry (with Mac Mini it's not that important) and a loss of speed/added latency for e.g. video editing. With normal usage patterns even USB 3.0 external thumb/SSD drives were just fine.
  - stephenr 8y ago
    So use a tb3 enclosure with an nvme inside.
    - Sephr 8y ago
      There are no bus-powered TB3 M.2 PCIe enclosures, and there never will be any[1]. This means you will have to buy a huge bulky externally-powered TB3 PCIe dock costing hundreds of dollars to accomplish this. 1. https://twitter.com/sephr/status/817883011165233152?s=19 https://twitter.com/sephr/status/817883011165233152?s=19
      - stephenr 8y ago
        No, it says there won’t be any that are sold unbundled.
  - rsync 8y ago
    "Still, another dongle to carry (with Mac Mini it's not that important) and a loss of speed/added latency for e.g. video editing. With normal usage patterns even USB 3.0 external thumb/SSD drives were just fine." What is the speed difference between the on-board PCIe connected SSD vs. the USB3 connected SSD ? Aren't both PCIe and USB3 faster than the SSD, making it the bottleneck ? A flash drive would, of course, be terribly slow ... do they make USB "thumb drives" that are SSD (not flash) ?
shaggerty 8y ago
Yes, if the soldered-on SSD has failed you can boot from an external drive by holding down the alt/option key while the system powers on to bring up the boot selection menu.
- Wowfunhappy 8y ago
  I thought this no longer works with the T2 chip? Don't you run into issues with e.g. upgrading the firmware because it will only accept firmware updates from the internal drive?
  - Foivos 8y ago
    I got a brand new mac with a T2 chip this week from my work. The first thing I did was do all the updates, including a security update for the OS, which required a restart. During the restart it was giving errors, so it was not able to boot properly. It would just give the error message and you could only restart again, just to have the same thing happen. A colleague more familiar with macs, brought up a menu, where you could choose which drive to boot from, which eventually fixed the problem, since it booted from the hard disk. In my case this menu had only the internal ssd, since I did not have anything else connected. I would guess that if I had an external hard drive it would show up as well. Also on the documentation of the T2 chip, Apple strongly recommends to use file vault, because if you do not, the ssd even though it is encrypted by default, gets decrypted [1] upon being mounted. To sum up, I guess it is possible to boot from whatever device you want. [1] https://support.apple.com/en-us/HT208344 https://support.apple.com/en-us/HT208344