[Discuss] Running things from initramfs

[worley at alum.mit.edu (Dale R. Worley)]

Here's a messy problem.  I suspect the answer is simple, but obscure:

I have an Oracle Linux (a Red Hat derivative) computer and I'd like to
run "xfs_repair /dev/mapper/ol-root".  The problem of course
is that partition is the root partition and xfs_repair can't operate
on a partition that's mounted.  If I could boot off a CD, it would be
simple, but since this computer is remote, that's hard to do.  I've recently
found that you can edit the "kernel boot line" to include
"rdinit=/bin/bash", and that causes the boot process to stop early,
with only the initramfs mounted and you talking to a Bash shell.

The problem is that this environment is not at all set up, and even
/dev is nearly empty.  There is an xfs_repair binary, so I figure if I
could just get /dev/mapper/ol-root set up correctly, I could
repair it.  There is an "lvm" binary, and it seems to support the
usual commands, but I can't get it to set up /dev/mapper.

When I run "lvm" it complains about (IIRC) /proc and /sys not
containing what it wants.  I've discovered that I can do "mount -t
proc non /proc" and similarly for /sys and those seem to work.  That
stops "lvm" from complaining but it doesn't cause it to populate
/dev/mapper.

Trying to trace how the normal boot works looks hard.  Among other
thngs, there seems to be a complete copy of systemd on initramfs!

Does anyone know how to get LVM working in this situation?

Dale