Bitcoin Core – Should Bitcoind be stopped when backing up chainstate/ and blocks/ directories?

Here’s how to back up your Bitcoin Core data directory to save future sync times.

#!/usr/bin/bash

local_d=/root/btc_db

rsync -av --delete chainstate "$local_d"
rsync -av --delete blocks "$local_d"

Sometimes backing up to a remote location takes quite a while, so there can be a lot of blocks delayed in between. rsync -av --delete chainstate "$local_d" and rsync -av --delete blocks "$local_d". Will Bitcoin Core synchronize smoothly when supplied? chainststate/ Backup directories corresponding to different block heights blocks/ directory?