Windows & Daylight Saving Time

by Ibrahim Tannir

October 31, 2014 – As some people may have noticed on their Windows installations, following the switch back from the daylight saving time (DST), P4 & P5 ran all the backup plans as if it was doing a full backup, regardless of the plan’s configured backup level.

This behavior is due to a bug in Microsoft’s basic ANSI/ISO compatibility package, that for some reason does not consider the daylight saving time. The consequence of this bug, is that all the files in the file system appear to have changed their modifications (and other) times.

Since P4/P5 checks the data that is logged in its index against the file system, any differences detected in the file system compared to what is noted in the index will trigger a new save of the data.

P5.1.7 works around Microsoft’s faulty behavior. However, since the modification time will now correctly and truthfully be delivered as it originally was prior to the DST switch, P5 will once again run its plans as if Full Backup was configured, since the latest run already noted the improper dates and times into the index.

 

Recommendation:

If one has run into the problem for files saved during DST and wishes to avoid the second round of full backups after updating to P5.1.7 until the actually planned full backup, the following setup is recommended:

  1. Edit the file C:\Program Files (x86)\ARCHIWARE\PresSTORE\config\lexxsrv.8000
  2. Add the following lines at the end:
  3. Restart P5

 

Further reading regarding this problem:
Microsoft’s Statement Regarding Daylight Saving Time

Please note that P4/P5 are fully NTFS aware and that Microsoft’s statement is misleading in this regard.