#!/bin/bash
#
pvcreate /dev/sdb /dev/sdc /dev/sdd
#
vgcreate lvmraid /dev/sdb /dev/sdc /dev/sdd
#
lvcreate -n raid5 --type raid5 -i 2 -L 30G lvmraid /dev/sdb /dev/sdc /dev/sdd
#
lvconvert --raidintegrity y lvmraid/raid5
#
mkfs.ext4 /dev/lvmraid/raid5
#
mount /dev/lvmraid/raid5 /mnt/hd/
#

lvm2-monitor.service

On RHEL8 (CentOS8) you can add the VG activation to /etc/systemd/system/sysinit.target.wants/lvm2-monitor.service

[Unit]
Description=Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling
Documentation=man:dmeventd(8) man:lvcreate(8) man:lvchange(8) man:vgchange(8)
Requires=dm-event.socket
After=dm-event.socket dm-event.service lvm2-activation.service
Before=local-fs-pre.target shutdown.target
DefaultDependencies=no
Conflicts=shutdown.target

[Service]
Type=oneshot
Environment=LVM_SUPPRESS_LOCKING_FAILURE_MESSAGES=1
ExecStart=/usr/sbin/lvm vgchange -ay
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ExecStart=/usr/sbin/lvm vgchange --monitor y
ExecStop=/usr/sbin/lvm vgchange --monitor n
RemainAfterExit=yes

[Install]
WantedBy=sysinit.target