CentOS - Jun 2005 - Software RAID muck up

Hi,

I hope someone can help.

Just started to play with software RAID on Centos 3.5 and was trying to 
simulate a faulty drive by using the -f switch on mdadm to mark the 
partition (drive) as faulty and I then I removed and readded the drive, 
which quit happily rebuilt according the /proc/mdstat and the output 
from the --detail switch of mdadm.  After all this mucking around I 
shutdown the system and tried to restart it in the morning but the 
system now won't boot, it gets as far as "GRUB loading" and just
stops I
have hard reset to get it to reboot.

I have rebooted using the install CD in rescue mode and I can see that 
all the arrays are setup quite happily (all RAID 1's if it matters) and 
mdstat reports the status as "dirty,no-errors".  Is that status
normal?
all the how-tos I've seen about software RAID show this as the status, 
so I have kind of assumed that is okay.

Given that all the data is readable from the arrays, I'm guessing that I 
had to do something to GRUB prior after rebuilding the arrays and before 
shutting down the system.

Can anyone help fill in the gap in my knowledge as to what I should have 
done?

Thanks for any help.

Regards

Lee

On Sat, 25 Jun 2005, Lee W wrote:
> I hope someone can help.
> 
> Just started to play with software RAID on Centos 3.5 and was trying to
> simulate a faulty drive by using the -f switch on mdadm to mark the
partition
> (drive) as faulty and I then I removed and readded the drive, which quit
> happily rebuilt according the /proc/mdstat and the output from the --detail
> switch of mdadm.  After all this mucking around I shutdown the system and
> tried to restart it in the morning but the system now won't boot, it
gets as
> far as "GRUB loading" and just stops I have hard reset to get it
to reboot.
> 
> I have rebooted using the install CD in rescue mode and I can see that all
the
> arrays are setup quite happily (all RAID 1's if it matters) and mdstat
reports
> the status as "dirty,no-errors".  Is that status normal? all the
how-tos I've
> seen about software RAID show this as the status, so I have kind of assumed
> that is okay.
> 
> Given that all the data is readable from the arrays, I'm guessing that
I had
> to do something to GRUB prior after rebuilding the arrays and before
shutting
> down the system.
> 
> Can anyone help fill in the gap in my knowledge as to what I should have
done?
You may want to look at this:

	http://forums.fedoraforum.org/showthread.php?t=26912

Not sure if it is the same cause, but worth to check.

Kind regards,
--   dag wieers,  dag at wieers.com,  http://dag.wieers.com/   --
[all I want is a warm bed and a kind word and unlimited power]

On Sat, 2005-06-25 at 09:48, Lee W wrote:
> Just started to play with software RAID on Centos 3.5 and was trying to 
> simulate a faulty drive by using the -f switch on mdadm to mark the 
> partition (drive) as faulty and I then I removed and readded the drive, 
> which quit happily rebuilt according the /proc/mdstat and the output 
> from the --detail switch of mdadm.  After all this mucking around I 
> shutdown the system and tried to restart it in the morning but the 
> system now won't boot, it gets as far as "GRUB loading" and
just stops I
> have hard reset to get it to reboot.
> 
> I have rebooted using the install CD in rescue mode and I can see that 
> all the arrays are setup quite happily (all RAID 1's if it matters) and
> mdstat reports the status as "dirty,no-errors".  Is that status
normal?
> all the how-tos I've seen about software RAID show this as the status, 
> so I have kind of assumed that is okay.
> 
> Given that all the data is readable from the arrays, I'm guessing that
I
> had to do something to GRUB prior after rebuilding the arrays and before 
> shutting down the system.
Grub doesn't actually boot from a RAID - it just happens to work
because RAID1 looks the same on the underlying single partitions.
Boot with the CD and point the grub config to one or the other
of the hd partitions holding /boot.  If you get an error, that
one might be corrupt and you can try the other.   If you get
to the point where the kernel is loaded and you can't mount
root, then the problem could be with RAID, but that part will
probably work.

-- 
  Les Mikesell
   les at futuresource.com

From: Dan Pritts <danno at internet2.edu>
> I just looked at that a few weeks ago - it doesn't seem to have reached
> critical mass.  Would sure be nice.
Oh, it _has_ reached "critical mass" among a lot of embedded and
application-specific capabilities.

But like most distribution channel issues, you can be sure that AMI,
Phoenix and others are fighting it quite hard.  Even Intel's so-called
"open" initiatives are still in the "tight knit group" of
BIOS vendors.

And Microsoft would love nothing more than to make it impossible
to access system configuration outside of Windows, Windows systems
unable to boot be damned.  Most hardware vendors are _also_ more
than happy to see this, because they can start tying hardware to
specific Windows versions.

Hence the entire "superstore" hardware/distribution issue that will
always plague Linux and partnerships to create Linux drivers.
> heck, i'd settle for getting serial-bios capability out of commodity
> motherboards.  "server" systems (and maybe high-end
"workstation"
> motherboards) have it but things like the via c3 boxes i have posted
> about before generally don't.  
I'm waiting to see what Apple cooks up.  They won't share it, but
it will possibly create enough stir to change the industry in general.


--
Bryan J. Smith   mailto:b.j.smith at ieee.org