Bug#777140: Using mdadm to install Debian on Intel RST RAID array stopped working between Wheezy 7.8 and Jessie RC1

[Benjamin Black]

On Fri, 06 Feb 2015 10:28:00 +0300 Michael Tokarev <mjt at tls.msk.ru> wrote:
> Control: retitle -1 Using mdadm to install Debian on Intel IMSM RAID
array stopped working between Wheezy 7.8 and Jessie RC1
> Control: reassign -1 mdadm
> Control: tag -1 + help
>
> 05.02.2015 17:43, Benjamin Black wrote:
> > Package: debian-installer
> > Version: used in Debian GNU/Linux Jessie-DI-rc1 "Jessie" - Official RC
amd64 CD Binary-1 20150109-01:06 image
> >
> > My UEFI motherboard has an Intel RST chip on it, which I use to set up
a pair of SSD drives in a RAID-0 array.  I have successfully installed
Debian Wheezy on this array in the past, using an expert set up and some
manual configuration during the install.  I tried repeating that process
using the Jessie RC1 installer, and it failed.
> >
> > For Wheezy, I used the image Debian GNU/Linux 7.8.0 "Wheezy" - Official
amd64 CD Binary-1 20150110-14:43
> >
> > For Jessie, I used the image Debian GNU/Linux Jessie-DI-rc1 "Jessie" -
Official RC amd64 CD Binary-1 20150109-01:06
> >
> > Both images were written to a USB stick, and both installers were
booted in UEFI mode.
> >
> > To do the installation, I run through the first few steps of the expert
install, up to and including detecting disks.  At that point, I switch to
the console (Alt-F2), to assemble and start the software arrays.  First I
load the kernel modules for RAID, which also loads the md_mod module, and
then I execute mdadm to assemble and start the arrays.
> >
> > When I do this in Wheezy, it successfully builds the arrays and starts
them:
> >
> > ~ # modprobe raid0
> > ~ # mdadm --assemble --scan --verbose
> > mdadm: looking for devices for further assembly
> > mdadm: /dev/sdb is identified as a member of /dev/md/imsm0, slot -1.
> > mdadm: /dev/sda is identified as a member of /dev/md/imsm0, slot -1.
> > mdadm: added /dev/sda to /dev/md/imsm0 as -1
> > mdadm: added /dev/sdb to /dev/md/imsm0 as -1
> > mdadm: Container /dev/md/imsm0 has been assembled with 2 drives
> > mdadm: looking in container /dev/md127
> > mdadm: found match on member /md127/0 in /dev/md127
> > mdadm: Started /dev/md/Boot_0 with 2 devices
> >
> > However, following the same steps in Jessie, mdadm fails to start the
array because of some file permission problem:
> >
> > ~ # modprobe raid0
> > ~ # mdadm --assemble --scan --verbose
> > mdadm: looking for devices for further assembly
> > mdadm: /dev/sdb is identified as a member of /dev/md/imsm0, slot -1.
> > mdadm: /dev/sda is identified as a member of /dev/md/imsm0, slot -1.
> > mdadm: added /dev/sda to /dev/md/imsm0 as -1
> > mdadm: added /dev/sdb to /dev/md/imsm0 as -1
> > mdadm: Container /dev/md/imsm0 has been assembled with 2 drives
> > mdadm: cannot open device /dev/md/imsm0: No such file or directory
>
> I don't see any permission problems in here, but indeed, mdadm is
> unable to complete the process.
>
> Since this has nothing to do with the installer really, -- you're
> trying to assemble the array manually using mdadm and it fails,
> I'm reassigning this bugreport to mdadm package.
>
> However, since I don't have hardware where I can test this, I'm
> tagging this as "help", -- because I can't debug it myself.  Maybe
> someone with the hardware will be able to understand what's going
> on.
>
> BTW, does /dev/md/ directory exists?
>
> Thanks,
>


A good question.


On WHEEZY, BEFORE running mdadm:
* There are no /dev/md[0-9]+ devices
* There is no /dev/md/ directory, and therefore no symlinks within it to
/dev/md[0-9]+ devices


On JESSIE, BEFORE running mdadm:
* There are no /dev/md[0-9]+ devices
* There is no /dev/md/ directory, and therefore no symlinks within it to
/dev/md[0-9]+ devices


On WHEEZY, AFTER running mdadm:
* There is a /dev/md125 device
* There is a /dev/md/ directory
* The /dev/md directory contains a symlink: Boot_0 -> ../md125
* Running parted on either the symlink or the device reports no errors, and
I can proceed with installation and it works


On JESSIE, AFTER running mdadm:
* There is a /dev/md126 device
* There is NOT a /dev/md/ directory, and obviously no symlinks
* Running parted on the device, "parted /dev/md126" reports:
    Warning: Error fsyncing/closing /dev/md126: Input/output error
    Retry/Ignore?


Note that Jessie does create different a different device than Wheezy:
/dev/md126 vs /dev/md125.  Might be relevant, might not.

Also, I discovered that I do not have to manually "modprobe raid0", running
mdadm will cause the modules to be loaded; however, I am still doing it to
reduce the possible sources of the problem.

Best,
BB
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