Doing it that way will rape disk I/O on your server, much better use ZFS snapshot then just zfs send & pipe thru xz/bzip2 to send it remotely

Example:

   #!/bin/bash
   TS=$(date "+%Y%m%d-%H%M%S")
   SNAP=zpool/mysql@${TS}
   zfs snapshot $SNAP
   zfs send $SNAP | pv | xz -z | ssh somewhere "cat > /mnt/snapshots/mysql-${TS}.xz"
   zfs destroy -Rv $SNAP

Assumes that your /var/lib/mysql is zpool/mysql ofc