So I had this script that would check the chain of PVs used for some LV
if used in an embedded VG.
Meaning an outer PV contains a VG contains a LV that is the PV to
another VG.
This script fails to work currently inside a chroot.
The reason is that not all VGs and LVs are visible inside the chroot.
Most importantly currently the PV is not visible.
I have bind mounted /sys/, /proc/, /dev/, and /run/.
Outside of the chroot, this is visible:
msata-pv coll2 -wi-ao---- 28.91g
raid-pv coll2 -wi-ao---- 464.36g
boot msata rwi-aor-p- 240.00m
root msata rwi-aor-p- 14.67g
The chroot is to a mount of /dev/msata/root.
Inside the chroot, to the /mnt of /dev/msata/root,
everything is now visible as well but only because lvmetad works because
I bind mounted /run.
vgdisplay -v inside the chroot gives:
--- Physical volumes ---
PV Name unknown device
PV UUID aCDiCd-EWYT-eKmE-gMST-KpXG-EJA5-0FWy8Z
PV Status allocatable
Total PE / Free PE 7399 / 3582
vgdisplay -v outside the chroot gives:
PV Name /dev/coll2/msata-pv
PV UUID aCDiCd-EWYT-eKmE-gMST-KpXG-EJA5-0FWy8Z
PV Status allocatable
Total PE / Free PE 7399 / 3582
If I remove the bind mount for /run, I get
msata-pv coll2 -wi-ao---- 28.91g
raid-pv coll2 -wi-ao---- 464.36g
But not the 2 msata volumes, that are both mounted inside the chroot
(/mnt and /mnt/boot).
The volumes are fully functional though. LVM just doesn't show me their
devices. Is this to be expected?
I was using the standard LVM tools to obtain this PV. It would be
possible to use only dmsetup etc. for it,
for example using dmsetup deps /dev/msata/root, to obtaining the name
with dmsetup info to see whether it is
conforming to an LVM mapping, but rather hard/impossible to see if it is
an actual regular LV this way?
Actually the split-name function... does not provide that much help for
that :p.
Particularly in this way it is not possible to see if something is a
"hidden" LV (such as a meta or image) or actually a regular LV that's
being referred to. I really wanted to say PV, but from the perspective
of the script you're really just looking for regular LVs.
The moment you encounter a non-major-252, I'm no longer interested :p.
But in any case:
Why does it not show the mounted LV in the "lvs" table and why does it
not show the PV that IS visible in the "lvs" table in the output of
"vgdisplay -v" ?
So, why is that PV set to "unknown device"? And with /run not
bind-mounted, pvscan will not see the msata volume group at all!
PV /dev/sdb4 VG coll2 lvm2 [493.26 GiB / 0
free]
PV /dev/coll2/raid-pv VG raid lvm2 [464.35 GiB / 8.00 GiB
free]
---> should also show /dev/coll2/msata-pv.
Maybe this gets a little too complicated,
but the msata volume group that is mounted into the chroot, is not
actually visible inside the chroot, while everything else is.
Regards, Xen.
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