Ensuring that rsync doesn't try to write to an unmounted drive

[Chris]

I have a script that runs nightly as a cronjob to backup my drive to a
USB drive https://pastebin.com/yivqrGUC On the command line I use the
--timeout option. Is this sufficient to ensure that if the external
drive somehow becomes unmounted that rsync will gracefully fail without
trying to write to the hard drive instead of the USB drive?

rsync -vaWSHpl --timeout=15 --delete-excluded --filter "merge
${EXC_FILE}" / "${BACKUP_DIR}" > /home/chris/rsyncbackup.log 2>
/home/chris/rsyncbackup.errors.log 

If this is sufficient or would it be better if I lowered the 'timeout'
to 5 seconds?

Thanks for any suggestions/advice.

Chris

-- 
Chris
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