Why a scheduled backup is not created at the requested time on Plesk server

Question

Scheduled backup is configured to begin at a specified time Backup Manager > Scheduled Backup Settings > Start backup creation at (HH:mm) .

However, creation of the backup is not started at the time when it was indicated. Why?

Answer

The scheduled backup is started the next time utility backupmng is executed if the scheduled period (24 hours) passed since the latest backup time. See details below:

According to the Plesk database, the scheduled backup for the server has the following configuration:

# plesk db "select obj_id, obj_type, last, period, active, backup_time from BackupsScheduled where obj_type='server'"
+--------+----------+---------------------+--------+--------+-------------+
| obj_id | obj_type | last | period | active | backup_time |
+--------+----------+---------------------+--------+--------+-------------+
| 1 | server | 2018-04-12 19:44:06 | 86400 | true | 19:53:00 |
+--------+----------+---------------------+--------+--------+-------------+

The backup task is executed by Plesk utility backupmng that is launched from root crontab :

# crontab -l
1,16,31,46 * * * * /opt/psa/admin/sbin/backupmng >/dev/null 2>&1

Or

# cat /etc/cron.d/plesk-backup-manager-task
0,15,30,45 * * * * root [ -x /opt/psa/admin/sbin/backupmng ] && /opt/psa/admin/sbin/backupmng >/dev/null 2>&1

The time of the task is set randomly during Plesk installation.

If there are a lot of the backup tasks scheduled at the same time, adjust 'Maximum number of simultaneously running scheduled backup processes' in Tools & Settings > Backup Manager > Backup Settings to appropriate value. By default, it is set to '2'. Mind that backup is resource-consuming task and setting this value to a high number may cause downtime.

If it is required to test the scheduled backup process right now, empty the value of psa.BackupsScheduled.last for particular backup task in Plesk database:

1. Make a backup of Plesk database: How to backup/restore a Plesk database dump.

2. Log into Plesk database.

3. Run following commands one by one:

   MYSQL_LIN: mysql> begin;
   mysql> update psa.BackupsScheduled set last='' where obj_id=1;
   mysql> commit;