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Daylight saving time 2017 in Europe began at 01:00 on Sunday 26 Marchand ends at 02:00 on Sunday 29 October (All times are in GMT).
We experienced a complete server stall due to an interesting combination of events all triggered by generating backups exactly on the time of the Daylight saving time change.
On Saturday quite some data was added 175GB. At exactly 02:00:00 (GMT +1) the backup preparation started and probably just after the time server updated the server time to 03:00:XX (GMT +1). The preparation took around 6 minutes. Starting the actual backup at 02:06:00 which was at that time actually 03:06:00.
This all got plesk backups confused resulting in failing backup processes and double entries; backups at 02:06 GMT +1) failed and backup of 03:06 (GMT +1) not created, server start to accumulate memory usage, eventually stalling due to kernel panic around 08:00 (GMT +1).
The backup was set to run at 02:00 (GMT +1), after the DST change Plesk seem to have changed this to 03:00 (GMT +1) on its own. With these two failed / incorrect after the required reboot Plesk decided to make another backup at 08:36 (GMT +1) that now as integrity issues (unreliable).
The assumed 'solution' here would probably be to never set backups on exactly on the time (00) when a DST change can happen in your timezone. Or in between the two times of a DST (02:00-03:00) to avoid the risk of double backups when summer to winter DST change. In my situation these times are 02:00 GMT+1 for winter to summer and 03:00 GMT+1 for summer to winter. So i now set my backups to 03:15 GMT +1.
Any thouhts / suggestions welcome.
Plesk / Igor: Might be smart to look into this scenario.
We experienced a complete server stall due to an interesting combination of events all triggered by generating backups exactly on the time of the Daylight saving time change.
On Saturday quite some data was added 175GB. At exactly 02:00:00 (GMT +1) the backup preparation started and probably just after the time server updated the server time to 03:00:XX (GMT +1). The preparation took around 6 minutes. Starting the actual backup at 02:06:00 which was at that time actually 03:06:00.
This all got plesk backups confused resulting in failing backup processes and double entries; backups at 02:06 GMT +1) failed and backup of 03:06 (GMT +1) not created, server start to accumulate memory usage, eventually stalling due to kernel panic around 08:00 (GMT +1).
The backup was set to run at 02:00 (GMT +1), after the DST change Plesk seem to have changed this to 03:00 (GMT +1) on its own. With these two failed / incorrect after the required reboot Plesk decided to make another backup at 08:36 (GMT +1) that now as integrity issues (unreliable).
The assumed 'solution' here would probably be to never set backups on exactly on the time (00) when a DST change can happen in your timezone. Or in between the two times of a DST (02:00-03:00) to avoid the risk of double backups when summer to winter DST change. In my situation these times are 02:00 GMT+1 for winter to summer and 03:00 GMT+1 for summer to winter. So i now set my backups to 03:15 GMT +1.
Any thouhts / suggestions welcome.
Plesk / Igor: Might be smart to look into this scenario.
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