Hello,

The mdadm 3.3 binary we've been using was compiled from source on a Debian
Wheezy 32-bit install, with the source downloaded from kernel.org

But also, this morning, I tried the same test with the 3.3 mdadm binary
taken from the Debian Jessie package here:

packages.debian.org slash jessie slash i386 slash mdadm slash download
(mdadm_3.3-2_i386.deb)

The results were the same, as this output shows:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mdadm: looking for devices for further assembly
mdadm: no RAID superblock on /dev/sdd4
mdadm: no RAID superblock on /dev/sdd3
mdadm: no RAID superblock on /dev/sdd2
mdadm: no RAID superblock on /dev/sdd1
mdadm: no RAID superblock on /dev/sdd
mdadm: cannot open device /dev/sr1: No medium found
mdadm: cannot open device /dev/sr0: No medium found
mdadm: no RAID superblock on /dev/sda11
mdadm: no RAID superblock on /dev/sda10
mdadm: no RAID superblock on /dev/sda9
mdadm: no RAID superblock on /dev/sda8
mdadm: no RAID superblock on /dev/sda7
mdadm: no RAID superblock on /dev/sda6
mdadm: no RAID superblock on /dev/sda5
mdadm: no RAID superblock on /dev/sda4
mdadm: no RAID superblock on /dev/sda3
mdadm: no RAID superblock on /dev/sda2
mdadm: no RAID superblock on /dev/sda1
mdadm: no RAID superblock on /dev/sda
mdadm: no RAID superblock on /dev/sdc1
mdadm: /dev/sdb is identified as a member of /dev/md/imsm0, slot -1.
mdadm: /dev/sdc2 is identified as a member of /dev/md/imsm0, slot -1.
mdadm: /dev/sdc is identified as a member of /dev/md/imsm0, slot -1.
mdadm: added /dev/sdc2 to /dev/md/imsm0 as -1
mdadm: failed to add /dev/sdc to /dev/md/imsm0: Device or resource busy
mdadm: added /dev/sdb to /dev/md/imsm0 as -1
mdadm: Container /dev/md/imsm0 has been assembled with 2 drives
mdadm: looking for devices for /dev/md/RAID0
mdadm: looking in container /dev/md/imsm0
mdadm: found match on member /md127/0 in /dev/md/imsm0
mdadm: Started /dev/md/RAID0 with 2 devices

I ran strace on this version with this command:
strace -o mdadm33trace.txt mdadm --assemble --scan --no-degraded

Here's a link to the strace output file:
www.dropbox.com slash s slash l5tcgu8zvjn7eb7 slash mdadm33trace.txt

On Mon, Nov 18, 2013 at 4:01 PM, NeilBrown [off-list ref] wrote:

On Mon, 18 Nov 2013 15:13:58 -0800 "David F." [off-list ref] wrote:

quoted

output of 'mdadm --assemble --scan --no-degraded -v' (mdadm 3.2.6):

...

quoted

mdadm: no RAID superblock on /dev/sdc2

quoted

output1 of 'mdadm --assemble --scan --no-degraded -v' (mdadm 3.3 -
note using /dev/sdc2, not /dev/sdc):

.....

quoted

mdadm: /dev/sdc2 is identified as a member of /dev/md/imsm0, slot -1.

So there is the problem.  mdadm 3.2.6 sees no RAID superblock on sdc2, while
mdadm 3.3 does (but should not).


However that code hasn't changed!

load_super_imsm() still starts with:


        if (test_partition(fd))
                /* IMSM not allowed on partitions */
                return 1;


and test_partition hasn't changed since it was written in April 2010 for
mdadm 3.1.3.

So I'm quite perplexed.

Is your mdadm-3.3 compiled from source or provided by a distro?

Can you run the "mdadm --assemble" under strace and post the result?

  strace -o /tmp/some-file mdadm --assemble --scan ......

Thanks,
NeilBrown