Having /dev/dm-1 mounted on /usr would not be an issue if it was
supposed to be that way; however, nothing in the handbook or anything
else I have read says that is correct. In addition, every other system
I have setup or used always had /usr as the mount point in the fstab.
My primary questions are:
* Why is it different this time?
* What changed to make /usr mount the block device?
* Why is the /usr record in the fstab being ignored and being handled
differently that /var, /opt, /home and /vm ?
Even though everything seems to be work correctly, without a good and
authoritative explanation my confidence level in the stability is not
too high and is preventing me from relying on it as primary host.
My concerns about not having a good explanation for why df -h shows
/dev/dm-1 on /usr instead of /dev/mapper/vg0-usr are:
* There could be problems interfacing directly with the block device
(/dev/dm-1) and not the link (/dev/mapper/vg0-usr).
* When it comes time to extend the /usr logical volume and use commands
like lvextend, resize2fs, lvresize and some others it may cause problems.
* The documentation does not say this is correct, in fact the
documentation specifically says the opposite that the fstab is used for
the mount points.
* It looks like the initramfs is not letting go of the temporary /usr
mount and mounting /usr in the vg0-usr volume group correctly.
After reinstalling Gentoo with a new liveusb, my system still looks
similar to the way it was before. I started with the existing partition
schema and wiped everything and performed a separate independent
install. I am still not sure why the /dev/dm-1 block device is mounted
on /usr which is not what the fstab is instructing.
UUIDs are not being used because the handbook says:
*Important:* UUIDs of the filesystem on a LVM volume and its LVM
snapshots are identical, therefore using UUIDs to mount LVM volumes
should be avoided.
/etc/fstab:
/dev/nvme0n1p6 /boot ext2
defaults,noatime 0 2
/dev/nvme0n1p7 none swap
sw 0 0
/dev/nvme0n1p8 / ext4
defaults,noatime,discard 0 1
/dev/nvme0n1p9 /lib/modules ext4
defaults,noatime,discard 0 1
/dev/nvme0n1p10 /tmp ext4
defaults,noatime,discard 0 1
/dev/mapper/vg0-usr /usr ext4
defaults,noatime,discard 0 0
/dev/mapper/vg0-home /home ext4
defaults,noatime,discard 0 1
/dev/mapper/vg0-opt /opt ext4
defaults,noatime,discard 0 1
/dev/mapper/vg0-var /var ext4
defaults,noatime,discard 0 1
/dev/mapper/vg1-vm /vm ext4
noauto,noatime,discard 0 1
/dev/cdrom /mnt/cdrom auto rw,exec,noauto,user 0 0
/etc/initramfs.mounts has:
/usr
# ls -l /dev/mapper/vg0-usr
lrwxrwxrwx 1 root root 7 Apr 23 05:56 /dev/mapper/vg0-usr -> ../dm-1
# mount /usr
mount: /usr: /dev/mapper/vg0-usr already mounted or mount point busy.
# df -h /usr
Filesystem Size Used Avail Use% Mounted on
/dev/dm-1 25G 3.2G 20G 14% /usr
Thank you
