On 2020-04-07 14:07, Terry Barnaby wrote:
I have a simple backup system that starts off a backup once per night during the weekdays. There is a crontab file in /etc/cron.d with the following entries:
################################################################################ # Beam Bbackup cron setup Backup to ... ################################################################################ # # Min Hour Day Month WeekDay
# Perform incremental backup to every work day 01 23 * * 1 root /src/bbackup/bbackup-beam 01 23 * * 2 root /src/bbackup/bbackup-beam 01 23 * * 3 root /src/bbackup/bbackup-beam 01 23 * * 4 root /src/bbackup/bbackup-beam 01 23 * * 5 root /src/bbackup/bbackup-beam
This system has been in use for 10 years or more on various Fedora versions. However about 18 months ago I have seen a problem where cron will start two backups with identical start times occasionally.
I have had to add a file lock system in the bbackup-beam to cope with this.
Any idea on why cron might start the same job off twice at the same time ? Could there be a time change issue with chronyd ?
I don't have an answer to your question. But wonder if using just
01 23 * * 1-5 root /src/bbackup/bbackup-beam
would help avoid the problem.
I assume the system is up 24/7?