date drift

[KenCunningham]

Hello all. I wonder whether anyone has experience of using the -a option to date to drift the time of a server by, say, 15 minutes (900 seconds)? I'm trying to do so because we have a number of half-hourly cron jobs which rely on accurate syncronisation of time between servers delivering data and those processing it. Once the time is set how I would like, I intend to use ntp to do the sync, but don't particularly wish to 'shock' the system by giving it a 15 minute advance all at once.

Any experiences, good or bad, gratefully received, particularly relating to how long such a drift might take. TIA.

 

[mrn]

Ken,

I've had problems using drift. It starts ok but then doesn't seem to bother about the last 15-20 seconds. It can take days to come into line. If it were me I'd be tempted to stop all app's change the time and reboot.

Everything you could ever wish to know regarding NTP can be found here

http://www.ntp.org/ntpfaq/

Mike

"A foolproof method for sculpting an elephant: first, get a huge block of marble, then you chip away everything that doesn't look like an elephant."

http://www.airport-parking-site.co.uk/

 

[KenCunningham]

Thanks for that Mike. NTP is working fine on a couple of our older servers, but for some reason the engineer setting up this one didn't seem to bother that the date was set 15 minutes out. I'm just trying drift on a sand box and will watch out for the symptoms you mention. I have a window at the weekend where I can take the system down if necessary. Thanks again.

 

[KenCunningham]

Well, everything appears to have gone well, and the server is now within a reasonable (for our purposes) time frame compared with the others. I will set up ntp on it, but wonder whether (in the light of what Mike said above), there is any way to confirm that the date -a has completed?

There doesn't seem to have been any evidence of the command in any ps listing when it was running, but it has obviously worked. I'd be interested to hear of any ideas people may have.