Can't boot from external usb drive

  bumpkin 17:16 07 Nov 2016
Locked

I have a USB3 caddy with Hdd which I wish to use as a backup drive. I have W10 on it but pc says "inaccessible boot device". Googled it and it seems quite a common error but could not find a solution. Any suggestions.

  Fruit Bat /\0/\ 19:37 07 Nov 2016

you can't boot windows from an external drive

  bumpkin 20:43 07 Nov 2016

Why is that?

What is your suggested solution for using an external drive as a backup for 2PC's. One has W10 and Win7 O/S the other Win10.

I want to use an external drive so that I can physically disconnect it in case of something nasty getting at my internal backup drives.

That sounds a bit blunt but not my intention, just a quick way to describe it.

  bumpkin 20:48 07 Nov 2016

If I can boot it from a usb stick, why not a usb drive.

  Fruit Bat /\0/\ 20:51 07 Nov 2016

Misunderstood thought you had win 10 on the external drive - windows is configured not to boot from and external drive. It can be done but its extremely fiddly, managed to do it with XP but never tried since.

Assume you are booting from normal windows with a USb 3 drive connected.

If you disable boot from USB in the BIOS it should work I have three external USB3 drives connected all the time The one with drive images on disable when not in use and therefore ransom ware cannot access it.

  bumpkin 21:19 07 Nov 2016

Thanks, I think I need to clarify the issue, I have win10 and win7 both on the external drive on different partitions. The external drive shows in bios and the boot choices menu. I have USB enabled in bios and will try disabling it. Getting confusing for me now.

  BRYNIT 21:30 07 Nov 2016

If it will not boot from any USB device it could be a setting in the bios. If in the bios it is set to UEFI it will not boot from a USB drive if you set it to legacy it will but it may not boot from the internal hard drive until you change it back to UEFI. If your bios allows Legacy+UEFI and you set it to this it will boot from both.

If you want to run a portable Windows from a USB CLICK HERE it will not run as fast as from an internal drive and the bios will need to be set to legacy or legacy+UEFI for it to work.

  BRYNIT 21:37 07 Nov 2016

"I have win10 and win7 both on the external drive on different partitions"

How did you install Windows 10 and Windows 7 onto this external drive on different partitions?

If you install Windows 10 and 7 while the hard drive was in the computer and then removed from computer and installed it into a USB caddy I doubt it would work.

  Fruit Bat /\0/\ 22:05 07 Nov 2016

windows is configured not to boot from and external drive.

  bumpkin 15:09 08 Nov 2016

windows is configured not to boot from and external drive.

OK, if that is the case then I assume that I will need to copy the backup onto an internal drive which is what I would do anyway but I won't know if the backup works until I require it. In fact to test it was the reason I wanted to boot from it.

  Fruit Bat /\0/\ 18:16 08 Nov 2016

What are you using to make the backups? I assume these are windows system backups?

When my anniversary update failed on me I found all the windows related stuff useless, startup repair, system restore, reset with or without saving data, and system backup image all failed.

luckily I had taken a Macrium Reflect image of the C: drive before doing the update date.

So my recommendation is to forget windows backups, make Macrium images of your drives and a rescue disk for when windows won't boot

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