md access permissions during early boot

[Tobias Roth]

I am working on an rc.d/ script that creates a memory file-backed
memory disk via mdconfig (the file exists already and contains a
valid ffs). After md creation, the device is checked with fsck_ffs -p.
However, fsck fails with the error NO WRITE ACCESS. The file
permissions of the md device under /dev/ are 640, which should not
prevent access. The same is true for the file itself, and the path
to it.

I tried passing the -o noreadonly option to mdconfig, but that didn't
result in any different behaviour.

My script is running right after the fsck script itself. When I
run it from the command line after successful boot and login,
fsck does not fail, so somewhere between the early beginning of
the rc.d/ sequence (right after fsck is run) and login, something
changes which results in root having access to my md.
                                                     
Any ideas what that could be? Another hint is that some time
around 5.3, this was not the default behaviour, fsck was possible
back then. I am using 6.0 stable now.

thanks, Tobias