Re: Fwd: Debian installer and raid0
Klaus wrote:
> Francesco Pietra wrote:
> >I forgot asking naively how to boot safely to the grub menu.
>
> When the system starts booting, the grub menu entries appear on
> screen. After a timeout (default 5 sec) the default entry is
> selected and the boot sequence continues. For details, here is the
> grub manual: <http://www.gnu.org/software/grub/manual/grub.html>.
Yes. And as soon as the menu appears the count down timer will
appear. 5..4..3..2..1..booting. Press any key on the keyboard and
the timer will stop counting and the system will wait at the menu.
Normally you woudl use up and down arrows to select an option. But
here the point is that if it makes it to the grub menu then grub's
boot sector has been installed on that disk drive. If grub has not
been installed then it will not get to that point and will fail
earlier.
By stopping at the grub menu when testing with one disk drive it
prevents booting to the system which would automatically update the
timestamps on the one solo raid1 disk that booted. That splits the
raid1 into two. If you reverse the disks and boot the second disk
then the timestamps on it would be newer. This is a "split brain"
problem. On a testing machine this isn't important because you can
just scrape it clean and set up the test again but it should be
avoided on a production machine. And even on a test machine it can
slow down the debugging if you decide you need to sync the raid. On a
debug system that is just useless cpu cycles wasted. That is why I
suggested avoiding it.
Bob
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