Find one unused disk on each OCP node supporting storage for use in e. g. creating a LocalVolumeSet

find-unused-disk

#!/bin/bash

read -r -d '' script <<'EOF'
for f in /dev/sd* ; do
    mountpoints="$(lsblk -J "$f" | jq -r '.blockdevices[0].mountpoints[]?')"
    if [[ -n "$mountpoints" && $mountpoints != "null" ]] ; then continue; fi
    children="$(lsblk -J "$f" | jq -r '.blockdevices[0].children[]?')"
    if [[ -n "$children" && $children != "null" ]] ; then continue; fi
    # If we immediately continued after finding a used disk
    # the find would get a broken pipe, which is ugly
    # albeit harmless
    failed=0
    if [[ -d /mnt/local-storage ]] ; then
	while read -r l ; do
	    if [[ $(readlink -f "$l") = "$f" ]] ; then failed=1; fi
	done <<< "$(sudo find /mnt/local-storage -type l -print)"
	if ((failed)) ; then continue; fi
    fi
    size="$(lsblk -J "$f" | jq -r '.blockdevices[0].size')"
    if [[ $size =~ ([0-9]+(\.[0-9]+)?)([KMGTP])? ]] ; then
	dsize=${BASH_REMATCH[1]}
	suffix=${BASH_REMATCH[3]}
	case "$suffix" in
	    K) scale=1000 ;;
	    M) scale=$((1000 * 1000)) ;;
	    G) scale=$((1000 * 1000 * 1000)) ;;
	    T) scale=$((1000 * 1000 * 1000 * 1000)) ;;
	    P) scale=$((1000 * 1000 * 1000 * 1000 * 1000)) ;;
	    *) continue ;;
	esac
	bytes=$(python3 <<< "print('%d' % ($dsize * $scale))")
	if ((bytes < 1500 * 1000 * 1000 * 1000)) ; then continue;fi
	echo "$f"
	break
    fi
done
EOF

while read -r node _ ; do
    disk=$(ssh core@$node "cat > /tmp/diskfinder && chmod +x /tmp/diskfinder && /tmp/diskfinder" <<< "$script")
    if [[ -n "$disk" ]] ; then
	printf "%s %s\n" "$node" "$disk"
    else
	echo "Can't find usable disk on $node" 1>&2
    fi
done <<< "$(oc get node --no-headers -l cluster.ocs.openshift.io/openshift-storage)"