You might want to look at these:
For usage of rsync, I can only offer up references posted regarding my own usage and coding for rsync-based backups. In my case, I have logic to perform that as independent jobs on each of the partitions on my 2 TB drive (each partition about 300 GB).
- My backup script and 2 external "script imports"
- Log of typical backup script session is included below.
Note that the posting has a full English translation at the bottom of the posting, after the code listings. 
LOG of backup session:
root@OasisMega1:/Oasis/bin# quickRSYNC.sh
NOTE: This script will ONLY perform synchronization backup (applying differences).
It does NOT perform a FULL COPY backup.
For FULL COPY backup, use 'OS_Admin__partitionSecondary_Mirror.sh' responding 'y' at the appropriate prompt ...
Forcing backup of all files. Option '--keepNewer' is available to keep backup version of files if newer ...
Checksum comparisons is disabled. Option '--compareFileData' is available to force this check by rsync ...
Following block devices have been identified:
sda 8:0 0 1.8T 0 disk
sdb 8:16 0 465.8G 0 disk
sdc 8:32 0 3.6T 0 disk
sr0 11:0 1 1024M 0 rom
External BACKUP disk is online ...
==============================================================================================
================================== PARTITION BACKUP START ==================================
==============================================================================================
SOURCE= /DB001_F1
MIRROR= /site/DB005_F8/DB001_F1 ...
Proceed with backup of 'DB001_F1' ? [y|N] =>
'DB001_F1' skipped ...
==============================================================================================
================================== PARTITION BACKUP START ==================================
==============================================================================================
SOURCE= /DB001_F2
MIRROR= /site/DB005_F2/DB001_F2 ...
Proceed with backup of 'DB001_F2' ? [y|N] =>
'DB001_F2' skipped ...
==============================================================================================
================================== PARTITION BACKUP START ==================================
==============================================================================================
SOURCE= /DB001_F3
MIRROR= /site/DB005_F3/DB001_F3 ...
Proceed with backup of 'DB001_F3' ? [y|N] =>
'DB001_F3' skipped ...
==============================================================================================
================================== PARTITION BACKUP START ==================================
==============================================================================================
SOURCE= /DB001_F4
MIRROR= /site/DB005_F4/DB001_F4 ...
Proceed with backup of 'DB001_F4' ? [y|N] => y
Using previously determined bandwidth limit for rsync buffer setting ...
Will apply parameter to limit flooding of I/O, memory and swap ==>> --bwlimit=65536
Mon 20 Jan 2025 06:54:07 PM EST |rsync| Start DB001_F4 ...
Background 'rsync' working ...
Expected Log files:
/site/DB005_F4/Z_backup.DB001_F4.DateSize.out
/site/DB005_F4/Z_backup.DB001_F4.DateSize.err
Use 'OS_Admin__partitionMirror_Monitor.sh' to monitor rsync process.
Imported LIBRARY: INCLUDES__TerminalEscape_SGR.bh ...
Mon 20 Jan 2025 06:54:17 PM EST
PID 19287 is RSYNC child process ...
PID 19286 is RSYNC child process ...
PID 19285 is RSYNC MASTER process ...
RSYNC backup process under way ...
root 19285 19281 0 18:54 pts/0 00:00:00 rsync
--bwlimit=65536
--one-file-system
--recursive
--outbuf=Line
--links
--perms
--times
--group
--owner
--devices
--specials
--verbose
--out-format=%t|%i|%M|%b|%f|
--delete-during
--whole-file
--human-readable
--protect-args
--ignore-errors
--msgs2stderr ./ /site/DB005_F4/DB001_F4/
Scanning at 10 second intervals ...
...............
RSYNC process (# 19285) has completed.
Mon 20 Jan 2025 06:56:50 PM EST
root@OasisMega1:/Oasis/bin#
Images of tail end of log with code-driven colouring:
