Back on Tuesday 21 March I wrote:
We run a default raid scrub regime (01:00 on Sundays). Last Sunday we got a message
Sun Mar 19 01:00:00 GMT [cron_admin]: Rescheduling raid_scrub_admin to run at Sun Mar 19 01:00:00 GMT 2000 because of Day Light Saving time change
[Raid scrubbing itself ran at this time with no problem.]
Moreover, every time timed tweaks the clock (we use ntp synchronisation) it again mutters. e.g.
Tue Mar 21 16:04:33 GMT [cron_admin]: Rescheduling raid_scrub_admin to run at Tue Mar 21 16:04:33 GMT 2000 because of Day Light Saving time change
Now all this is no doubt because next Sunday is clock-changing day in our timezone (GB), with 2000-03-26 01:00:00 GMT -> 02:00:00 BST. [American friends will no doubt be seeing this effect next week!]
Well, they obviously didn't, and I think I understand why. Contrary to my initial impression, it seems that the USA switches at 02:00:00->03:00:00 (local time), rather than 01:00:00->02:00:00.
The messages apparently only happen if the (local) time that the raid scrub is scheduled for does not logically exist. This happened in the UK and in the Republic of Ireland (I got a confirmation from Garret Flynn) and presumably in Portugal (any NetApp users there?). Further east in Europe the clock change is later in local time (because it is at the same real time, 01:00:00 UTC).
For those interested: the raid scrub *did* run at the expected time on clock-changing night, and the messages then disappeared.
Garret tells me that this is a known bug, 13649.
Chris Thompson University of Cambridge Computing Service, Email: cet1@ucs.cam.ac.uk New Museums Site, Cambridge CB2 3QG, Phone: +44 1223 334715 United Kingdom.