Re: Looking for some advice on best way to identify drives / recover from issues

[Krzysztof Adamski <k@adamski.org>]

Boot with knoppix CD and examine the drives without MD starting. This is
after you remove the highpoint card.

This way you can figure out what drives belong to which array.
If you can use lsdrv while running from knoppix.


On Sun, 2014-01-05 at 12:06 -0500, Dylan Distasio wrote:
> Thanks for the trick.  The issue of complicating things with MD is
> what I am concerned about.  I am afraid to boot the PC up with drives
> missing (if for example I remove the highpoint controller) because it
> may end up assembling an array with drives missing and degrading it
> when it didn't need to be.
> 
> I'm really wishing I had labeled my drives now, since I don't know
> which ones are part of which array physically, and don't want any
> arrays to assemble until I do.  I was wondering if booting into a live
> CD would be the way to go.  I need some way of checking which drive is
> in which array without the risk of any arrays assembling.
> 
> On Sun, Jan 5, 2014 at 11:33 AM, Roger Heflin <rogerheflin@gmail.com> wrote:
> > The crude but simple way is this:
> >
> > Get the machine up with all disks that will work.
> >
> > dd if=/dev/mdX of=/dev/null on each array, noting which disks light
> > up, repeat on all arrays, same process can be done with each disk (dd
> > if=/dev/sdX of=/dev/null ) to see exactly what disk maps to where.
> > This trick is rather nice since it pretty much works with
> > everything...even if you have a hw raid controlled and a failed disk,
> > that will be the one disk that never lights, so you can find the
> > failed on there also, just make sure that when done you have the
> > expected number of disks to not light up.
> >
> > The biggest issue is that if the md's come up missing the 4 drives it
> > may complicate things with MD, though at worse that should require
> > some usage of the raw mdadm command to force things on after doing
> > this.
> >
> > On Sun, Jan 5, 2014 at 9:04 AM, Dylan Distasio <interzone@gmail.com> wrote:
> >> Hi all-
> >>
> >> I''ve been fortunate enough to not have to email this august group for
> >> advice regarding my mdadm arrays in quite awhile, but am looking for
> >> some suggestions.
> >>
> >> I woke up this morning to something beeping in my headless Norco
> >> server case at home (never a promising start to the morning).  I was
> >> unable to ping the box which increased my dismay.  I proceeded to
> >> perform a hard reboot, and still nothing on the ping.  At this point,
> >> I plugged a monitor in to see what was happening on reboot.
> >>
> >> Let me take a moment to provide details of my basic set up.  There are
> >> three separate HD controllers being used in this box: the motherboard
> >> headers, a supermicro PCI-X card (in a PCI slot), and a Highpoint
> >> RocketRaid SAS controller used as JBOD.
> >>
> >> I have a number of separate mdadm arrays tied to this physical box
> >> that have been built over the years including a RAID6 one, a RAID10,
> >> and 2 mirrors.
> >>
> >> Unfortunately, I did not take the time to physically label the drives
> >> in the box (there are close to 20) as I built these, and had been
> >> meaning to, but life got in the way.  Since I have had no issues with
> >> these arrays in a very long time, I don't even remember if I split
> >> them across controllers or what.
> >>
> >> So back to the reboot, I can see the motherboard drives showing up as
> >> the POST runs through its paces.  I can then see what appears to be
> >> the Supermicro drives showing up, but when the Highpoint controller
> >> gets to it own internal boot screen, it hangs at detecting drives, and
> >> I am unable to get into the controller card BIOS by hitting ctrl-H
> >> (keyboard works though, as I can ctrl-alt-delete, so it is not locking
> >> the PC).
> >>
> >> So at this point, I don't know my point of failure.  I am guessing the
> >> Highpoint flaked out though, especially since I now believe that was
> >> the component beeping based on the PC restarting ok otherwise.
> >>
> >> I am looking for advice on minimizing my risk of making things worse
> >> as I attempt to identify what drives belong which with array.   The
> >> RAID6 is my most immediate concern in getting back up and running.
> >>
> >> My immediate thought was to disconnect all drives and then reconnect
> >> them one by one from a motherboard header, and use:
> >>
> >> mdadm --examine /dev/sdX1
> >>
> >> Will that give me enough info to figure out which drive belongs to
> >> which array?  Does anyone have any other suggestions?  I am not sure
> >> of the current state of ANY of the arrays that were on this box, but I
> >> don't want to make things worse by booting this system up with some
> >> drives missing because I've unplugged them, and having the a bad
> >> situation get worse.
> >> --
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