Add the SSD to the LVM as Cache
Update for Proxmox 6
It is necessary to add the following modules to the initramfs.
echo "dm_cache" >> /etc/initramfs-tools/modules
echo "dm_cache_mq" >> /etc/initramfs-tools/modules
echo "dm_persistent_data" >> /etc/initramfs-tools/modules
echo "dm_bufio" >> /etc/initramfs-tools/modules
update-initramfs -u
Disable LVM Cache
To reverse the above procedure please run the following command.
lvconvert --uncache pve/data