Re: mdadm problems with partitioned md devices

On Tuesday November 23, c-d.hailfinger.kernel.2004@gmx.net wrote:

Hi,

[please CC: me]
while trying to use md to overcome limitations of dm, I
stumbled upon the following problem: It is impossible to
have more than 4 partitioned md devices since mdadm will
create the 5th device with major:minor 255:0, which is
bogus.

You need user-space (libc in particular) that supports the new 32bit
device numbers in 2.6.  I don't know which version of glibc that would
be, or which distributions support it.  debian/unstable (which I use)
doesn't support it yet :-(

You could test your distribution with
   mknod /tmp/test b 253 1024
   ls -l /tmp/test
   rm /tmp/test

and see if the major/minor is reported as "253, 1024" or "253, 0".
If the later, you need new glibc.
If the former, your userspace is up-to-date but there must be a bug in
mdadm.
If this is the case, let me know and I will look into it.

NeilBrown