Maybe
@waltar got this right already (apologies if I am slow), but from what I can see (this is summary for myself or someone else if they take over), maybe also you:
You do not have a probllem that you (as described in OP) "cannot mount my physical storage disk which had previously been mounted".
Technically, you have your physically ~1TB (give or take, let's not worry about this now) drive mounted on the PVE node (host), it happens to be XFS (shown as sda1 on the host) it is indeed 100% full.
This is mounted on the host into
/mnt/pve/storage
.
In there, you have your "virtual" disk for VM stored as QCOW2 image - this is basically a file on that XFS filesystem on that physical drive.
It has 1065314680832 bytes which is ~1TB and it appears to be completely filling up that entire host disk's filesystem of XFS.
You are then mounting this QCOW2 image into your VM (/dev/sdb on the guest as ext4 - that's filesystem of that image).
** I literally apologise if you knew all this, but it was not clear to me so far. **
At this point, I would probably take a step back, shut down the VM.
Then I would try to mount the QCOW2 directly on the host, you would need:
Code:
modprobe nbd
qemu-nbd --connect=/dev/nbd0 /mnt/pve/storage/images/444/vm-444-disk-0.qcow2
Let's see if that works out without errors.