Bug#777140: Using mdadm to install Debian on Intel RST RAID array stopped working between Wheezy 7.8 and Jessie RC1
Package: debian-installerVersion: 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
However, following the same steps in Jessie, mdadm fails to start the array because of some file permission problem:
Consequently, while I can proceed to the next installer step in Wheezy, because the system sees the RAID array and I can create partitions on it, in Jessie, the array is never started, no /dev/md/ device is created, and I cannot continue.
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