Re: booting a clone from a /dev/md0 disk as single ext4 disk

[John Griessen]

On 10/23/2016 12:03 PM, Andrei Borzenkov wrote:
> Sorry, I could not parse this sentence. What I'd do,
>
> 1. create target devices (presumably, Linux MD)
> 2. copy from source to target
> 3. adjust /etc/fstab, /etc/mdadm.conf and whatever else is appropriate
> (which may include recreating initrd)
> 4. chroot and run grub-install and grub-mkconfig or your distro command
> that calls them
>
> Note that in case of Linux MD grub2 grub-install only supports
> installation on MBR. You also need to install grub2 individually on each
> disk that belongs to MD array holding /boot/grub if you want resiliency
> against individual disk failures.
>
> Also note that in relation to grub2 "Linux MD" is really relevant only
> if grub2 itself (i.e. /boot/grub directory) is on MD array.
>
> 5. configure your distro to use new bootloader location(s) as default.
> So next time you update grub2 package it runs grub-install with correct
> parameters. In case of Debina-based distro this actually means running
> dpkg-reconfigure.


I found my main problem was a wrong rsync copy.  I had been doing rsync -acHv
and I noticed my scripts had become  rsync -aCHv which is filtering out many 
files needed
to run.   I decided that MD raid was not so helpful in my workstation use
as having really good robust backups incrementally happening with rsync,
and easy to restore by just booting a different disk and occasionally removing 
a disk,
putting it on shelf for hacker safe backup.  I don't seem to need a chroot to 
get
a rsync copy of a running drive to boot OK.  I just stop networking and 
thunderbird
and firefox and run rsync until there are just a few log files difference and 
call
that a good bootable backup.

I have my debian grub-pc package pinned at 2.02~beta2-22+deb8u1 for now.  Grub2 
is
working well with a GPT partitioned disk now.  Everything seems high 
reliability!

Thanks for the help.

John Griessen