I was asked to investigate snapshots on lvm. I still prefer ZFS over LVM, but if you only have LVM you at least have lvmsync ( Thanks to Matt for his fine work on https://github.com/mpalmer/lvmsync )

remote_lvsync_example.sh

#!/bin/bash
# this must exit on any error
set -e

initiate_pull_snapshots(){
  ssh ${DEST_HOST} lvcreate --size 10 --snapshot --name ${LOGICAL_VOL}-current  ${VOL_NAME}/${LOGICAL_VOL}
  ssh ${DEST_HOST} dd if=/dev/${VOL_NAME}/${LOGICAL_VOL}-current bs=1M | dd of=/dev/${CLOUD_VOLUME}/${LOGICAL_VOL} bs=1M
}

#    NB: The disk must have ${CHANGE_SIZE} space free to store all of the changes untill the next snapshot
#    *** If the changes are greater than ${CHANGE_SIZE}, the snapshot becomes corrupt, thus loosing all changes since.

loop_in_cron_pull(){
  ssh ${DEST_HOST} lvcreate --size ${CHANGE_SIZE} --snapshot --name ${LOGICAL_VOL}-new  ${VOL_NAME}/${LOGICAL_VOL} 
  ssh ${DEST_HOST} lvmsync --stdout /dev/${CLOUD_VOLUME}/${LOGICAL_VOL}-current  | lvmsync --apply - /dev/${VOL_NAME}/${LOGICAL_VOL} 

  # THE FOLLOWING MUST NOT RUN UNTILL ${VOL_NAME}/${LOGICAL_VOL}-current has succefully transfered! 
  #
  ssh ${DEST_HOST} lvremove -f ${VOL_NAME}/${LOGICAL_VOL}-current
  ssh ${DEST_HOST} lvrename    ${VOL_NAME}/${LOGICAL_VOL}-new  ${VOL_NAME}/${LOGICAL_VOL}-current
}