mk-lvm-snapshots-13g.service

[Unit]
Description=make LVM snapshots
Requires=local-fs-pre.target
DefaultDependencies=no
Conflicts=shutdown.target
After=local-fs-pre.target
Before=local-fs.target

[Install]
WantedBy=multi-user.target

[Service]
Type=oneshot
ExecStart=/sbin/lvcreate -L13G -n snap-root -s /dev/system/root