Re: Grub2 reinstall on raid1 system. Corrections!!!!!
On Mon, 17 Jan 2011 20:43:16 -0700
Bob Proulx <bob@proulx.com> wrote:
> Jack Schneider wrote:
> > Bob Proulx wrote:
> > > mdadm --stop /dev/md125
> > > mdadm --assemble /dev/md0
> > > --update=super-minor /dev/sda1 /dev/sdc1
> > >
> > > mdadm --stop /dev/126
> > > mdadm --assemble /dev/md1
> > > --update=super-minor /dev/sda5 /dev/sdc5
> >
> > Bob, a small glitch. mdadm:/dev/sda1 exists but is not an md array.
> > mdadm --stop was successful, before the above.
>
> If mdadm --stop was successful then it must have been an array before
> that point. So that doesn't make sense. Double check everything.
>
> mdadm --examine /dev/sda1
> mdadm --examine /dev/sdc1
> mdadm --detail /dev/md0
>
> > It appears that a "--create"-like command is needed. Looks like
> > md125 is md0 overwritten somewhere...
>
> If you "create" an array it will destroy the data that is on the
> array. Unless you want to discard your data you don't want to do
> that. You want to "assemble" an array from the components. That is
> an important distinction.
>
> You really want to be able to assemble the array. Do so with one disk
> only if that is the only way (would need the mdadm forcing options to
> start an array without all of the components) and then add the other
> disk back in. But if the array was up a moment before then it should
> still be okay. So I am suspicious about the problem. Poke around a
> little more with --examine and --detail first. Something does seem
> right.
>
> > Additionally, maybe I'm in the wrong config. Running from a
> > sysrescuecd. I do have a current Debian-AMD64-rescue-live cd.
> > Which I made this AM.
>
> That would definitely improve things. Because then you will have
> compatible versions of all of the tools.
>
> Is your system amd64?
>
Yes, a Supermicro X7DAL-E M/B with dual XEON quad core 3.2 ghz
processors and 4 Seagate Barracuda drives. 8 gigs of Ram.
> > I need to find out what's there...
> > further:
> > Can I execute the mdadm commands from a "su" out of a busybox
> > prompt?
>
> If you are in a busybox prompt at boot time then you are already root
> and don't need an explicit 'su'. You should be able to execute root
> commands. The question is whether the mdadm command is available at
> that point. The reason for busybox is that it is a self-contained set
> of small unix commands. 'mdadm' isn't one of those and so probably
> isn't available. Normally you can edit files and the like. Normally
> I would mount and chroot to the system. But you don't yet have a
> system. So that is problematic at that point.
>
> Bob
This AM when I booted, (I powerdown "init 0" each PM to save power &
hassle from S/O) the machine did not come up with grub-rescue prompt.
It booted to the correct grub menu then to Busy Box. I am thinking it
goes to BB because it can't find /var and or /usr on the md1/sda5 LVM
partition. I checked /proc/mdstat and lo & behold there was md1:active
with correct partitions and md0: active also correct partitions... I
must have been seeing md125 et al from only the sysrescuecd 2.0.0. So
here I sit with a root prompt from Busy Box.... I checked mdadm
--examine for all known partitions and mdadm --detail /mdo & /md1 and
all seems normal and correct. No Errors.
I seem to need a way of rerunning grub-install or update-grub to
fix this setup. What say you?? I am thinking of trying to start the
/etc/grub.d demon.
Jack
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