Re: [gentoo-user] Problems with Nvidia fake raid array

[Jeff Cranmer <jeff@lotussevencars.com>]

Is there anyone who can help me recover my raid array?

On Wed, 2011-07-20 at 20:43 -0400, Jeff Cranmer wrote:
> On Tue, 2011-07-19 at 09:06 -0400, Michael Orlitzky wrote:
> > On 07/18/2011 11:08 PM, Jeff Cranmer wrote:
> > > 
> > > 
> > > Pardon my additional questions before taking the plunge here.  
> > > 
> > > So, given that I have three devices, /dev/sda, /dev/sdb and /dev/sdc, if
> > > I run the command mdadm --assemble --scan, would this find all the
> > > components and create a /dev/md0 disk without damaging the contents of
> > > the original RAID array?
> > 
> > If you've got the space and time, a backup can't hurt. Using --scan will
> > make it check the config file, but right now, there's probably nothing
> > useful in it. This looks like what you want to do to me:
> > 
> >   If the --scan option is not given, then only devices and identities
> >   listed on the command line are considered.
> > 
> >   The first device will be the array device, and the remainder will be
> >   examined when looking for components.
> > 
> > but I'd figure out where that md0 is coming from (below) first.
> > 
> When I tried mdadm --assemble --scan with nothing uncommented in the
> configuration file, I got
> mdadm: No arrays found in config file or automatically.
> Typing dmesg | grep md0 returned no lines.
> 
> There are a couple of lines in dmesg when I run dmesg | grep md:, but
> they read
> md: linear personality registered for level -1
> md: raid0 personality registered for level 0
> md: raid1 personality registered for level 1
> md: raid10 personality registered for level 10
> md: raid6 personality registered for level 6
> md: raid5 personality registered for level 5
> md: raid4 personality registered for level 4
> md: Waiting for all devices to be available before autodetect
> md: If you don't use raid, use raid=noautodetect
> md: Autodetecting RAID arrays
> md: Scanned 0 and added 0 devices
> md: autorun...
> md: ... autorun DONE.
> 
> I think this means that raid5 is set up correctly in the kernel, but it
> can't find the raid array.
> 
> Next I tried adding a line to the config file:
> 
> DEVICE /dev/sda /dev/sdb /dev/sdc
> mdadm --assemble --scan returned the same results as before
> 
> Next, I tried commenting out the previously added DEVICE line, and
> adding
> ARRAY /dev/md0 devices=/dev/sda,/dev/sdb,/dev/sdc
> 
> mdadm --assemble --scan returns something different
> mdadm: /dev/sdb has no superblock - assembly aborted.
> > 
> > > The only item in /dev/mapper is th default 'control' entry.  There is
> > > a /dev/md0 item already listed, but presently when I try to mount it, it
> > > reports that it is unable to read the superblock.  Would the command
> > > above fix this?
> > 
> > Depends. Where'd the md0 come from? You probably have something in your
> > logs or dmesg, unless that device was created manually on your old system.
> > 
> > 
> > > Where is the config file mentioned in your e-mail, and do I need to edit
> > > it first to add the three raid disks?
> > 
> > It's /etc/mdadm.conf. You don't need it to create or use the array, but
> > you'll want to run mdadm when the machine boots and the config file
> > tells it what to do. Once the array is working, you can just do,
> > 
> >   mdadm --detail --scan >> /etc/mdadm.conf
> > 
> mdadm --detail --scan returns no output.
> 
> Also, I just checked /dev and md0 is now gone from the list.
> 
> Since there are also /dev/sg0, /dev/sg1 and /dev/sg1, I also tried those
> instead of /dev/sda, /dev/sdb and /dev/sdc in the ARRAY line, but mdadm
> --assemble --scan returned no output
> 
> I tried re-booting, but /dev/md0 is now permanently gone.
> 
> Does this give you any ideas what I can try next??
> 
> Thanks
> 
> Jeff
> 
> 
>