external installation question

[John G. Heim]

If you boot from an external hard drive, you can't eject and/or unmount 
it. The operating system won't allow it. What you want to say, I think, 
is that if you are booting from an external drive, whether it be an 
external hard drive or a flash drive, you should always do a shutdown 
before turning off your machine or disconnecting the  drive.

Really, what you need to do is sync the drive. There is an old command, 
"sync" that does that. You can probably then do whatever you want. 
Obviously, you'll hang your machine if you boot from a flash drive, do a 
sync, and then remove the flash drive.But you could probably just plug 
the drive back in and reboot.

In fact, you can probably get away with booting from a flash drive, just 
yanking it out, then putting it back in and rebooting.  But there you 
are playing the odds and there is no guarantee.






On 05/30/14 08:26, Paul Merrell wrote:
> On Fri, May 30, 2014 at 5:46 AM,  <aerospace1028 at hotmail.com> wrote:
>
>> If I understand correctly--once I get everything loaded on the external
>> drive and the boot order fixed--with the drive attached to my computer, I
>> will have the option to boot into archlinux, and with the drive
>> disconnected--while the machine is powered off--booting the machine will
>> revert to automatically jumping into the factory-installed Windows-7.  The
>> net effect should be similar to when I boot the live-CD: without the cd in
>> the tray (or this case the external drive plugged into the computer), my
>> computer will have no clue there are any other operating systems in
>> existance and just go happily on its way?  or as happily as my machine gets?
>
> Not sure about archlinux's auto-recognition of USB devices. It works
> that way on other recent distros I use or have used.
>
> The big difference between a USB drive and a CD drive, from a user
> standpoint, is that you *must* dismount the USB drive before you
> disconnect it from the machine unless the machine is turned off. Some
> distros call this "ejecting" the drive, although it does not
> physically eject the drive.
>
> With a USB 3 hard drive, you may wish to disconnect it when not in use
> to save wear and tear from spinning. If you do, be sure to dismount it
> before disconnecting *every* time. Disconnecting a USB thumb or hard
> drive without dismounting it first will almost always cause grief on
> Linux, sometimes resulting in an unusable drive. Much more commonly,
> you'll hit difficulties in mounting it. There is probably a way to fix
> such problems on Linux. But because I also have a Windows 7 system, I
> have fixed most such problems by plugging the drive into the Windows
> machine. In most cases, Windows will fix the problem without any extra
> effort on my part. Then back to the Linux machine.
>
> But I'm looking for a more trustworthy backup solution than an
> external USB 3 drive. Too many problems, with three different
> brands/models so far.
>
> Best regards,
>
> Paul
>
>
>

-- 
---
John G. Heim, 608-263-4189, jheim at math.wisc.edu