Re: RAID1 all bootable
Hi Lennart, Hi Simon
A proper understanding of mdadm is required. Hurrying with focus on
codes for biochemical applications has brought me into a mess.
Relying of all my data, and special compiled programs, present on
another raid1 amd64 wheezy, I carried out a reinstall of amd64 wheezy
on the machine with new HD. mdo (boot, ext20, md1 (LVM, home, usr,
etc). GRUB was installed on /dev/sda
Then the command
grub-install /dev/sdb
with reported installation compete. No errors reported.
On rebooting, GRUB was no more found, entering in
grub rescue >
which should also be known accurately, because prefix/root/ are now wrong.
The only care I exerted, was not to work with the machine where I have
my data, until the damaged machine is in order again. At any event,
how to install safely GRUB on both disks of a RAID1 is a must.
Thanks for your kind advice.
francesco pietra
As to mdadm,
On Sat, Mar 2, 2013 at 7:05 AM, Simon Vos <simonvos@gmail.com> wrote:
> Have you assembled you raid devices again (mdadm --assemble /dev/mdX
> /dev/sdX)?
>
> That should still work with the disk that was used for your RAID-1, when
> that's done you can mount your disk, chroot into it and run grub-install
> /dev/sda (and grub-install /dev/sdb, so you won't have this problem in the
> future ;-)).
>
>
> On 2 March 2013 11:10, Francesco Pietra <chiendarret@gmail.com> wrote:
>>
>> A further piece on information. With knoppix 7.0, the procedure for
>> examining mdadm arrives at
>>
>> cat /proc/partitions
>> sda
>> sdb
>>
>> RAID1 (md0 md1) is not seen. I assume that this is the way Knoppix
>> behaves in this situation.
>>
>> Thanks
>> francesco pietra
>>
>>
>> ---------- Forwarded message ----------
>> From: Francesco Pietra <chiendarret@gmail.com>
>> Date: Sat, Mar 2, 2013 at 10:11 AM
>> Subject: Re: RAID1 all bootable
>> To: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>, amd64 Debian
>> <debian-amd64@lists.debian.org>, debian-users
>> <debian-user@lists.debian.org>
>>
>>
>> Is this recipe devised for installing grub on both sda and sda with an
>> undamaged RAID1?
>>
>> In my case, with the sda that contained grub loader replaced by a new
>> disk, the rescue mode (using the same CD installer for amd64 wheezy)
>> did not find any partition. Inverting the SATA cables, same result.
>>
>> In both cases (I mean position of SATA cables) I went to the shell in
>> the installer environment:
>>
>> #fisk /dev/sda (or sdb)
>> device contains neither a valid DOS partition table, nor Sun, etc
>> (expected for a raid)
>>
>> #dmesg |grep -i sd
>> sda (and sbb): unknown partition table (expected for a raid), however
>> md: raid0
>> md: raid1
>> were identified, along with rai4, 5, 6 etc (unfortunately "| less"
>> does not work to see the whole message).
>>
>> Am I using the Rescue Mode improperly? I was unable to dig into the HD
>> that contains md0 (booth loader, EXT2) and md1 ( LVM partitions home
>> tmp usr opt var swap EXT3)
>>
>> Thanks a lot for your kind advice
>>
>> francesco pietra
>>
>>
>>
>> On Fri, Mar 1, 2013 at 10:35 PM, Lennart Sorensen
>> <lsorense@csclub.uwaterloo.ca> wrote:
>> > On Fri, Mar 01, 2013 at 08:20:09PM +0100, Francesco Pietra wrote:
>> >> Hi:
>> >> With a raid1 amd64 wheezy, one of the two HDs got broken.
>> >> Unfortunately, I had added grub to sda only, which is just the one
>> >> broken. So that, when it is replaced with a fresh HD, the OS is not
>> >> found. Inverting the SATA cables of course does not help (Operative
>> >> System Not Found). In a previous similar circumstance, I was lucky
>> >> that the broken HD was the one without gru.
>> >>
>> >> Is any way to recover? perhaps through Knoppix? I know how to look
>> >> into undamaged RAID1 with Knoppix.
>> >>
>> >> Also, when making a fresh RAID1 from scratch, where to find a Debian
>> >> description of how to make both sda and sdb bootable? (which should
>> >> be included by default, in my opinion)
>> >
>> > You can boot the install disk in rescue mode, select the root partition
>> > to chroot into, then run grub-install from there.
>> >
>> > When grub asks where to install, you should configure it for both sda
>> > and sdb. I think 'dpkg-reconfigure grub-pc' is where that is selected.
>> > Might need it to use -plow to asks all levels of questions. Not sure.
>> >
>> > --
>> > Len Sorensen
>>
>>
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