BewareDaylightSavingTime

From RdiffBackupWiki

If you are unfortunate enough to live in a region that practices this bizarre clock foulup twice a year, you should keep it in mind, especially for restore operations. Rdiff-backup's "restore as of" switch assumes the date and time are given in the current time zone, but the date specified may fall within a different one.

For instance, if today is 2009-06-21 and you run a restore-as-of 2009-01-01 00:00, you will actually get a restore as of 2008-12-31 23:00 because on January first your time zone was different by one hour. That might matter if your backups are scheduled to run at midnight.

You can get around this by specifying the time zone in the date argument (if you can remember which one your winter time corresponds to).

Also remember that on the days when a time zone switch occurs there is either an hour that doesn't happen (when advancing from standard time to daylight time) or an hour that happens twice (when falling back from daylight to standard time), i.e. there is one 23-hour day and one 25-hour day per year.