Uhm... sort of...

Niels is essentially correct and for the most of us, just starting an NNTPd on a server that sync's with a government clock and then your local servers sync to that... will be enough. However... in more detail...

Time is relative. ;-)

Ok... being a bit more serious...

There are two things you have to consider... What is meant by 'cluster time'?  and What you want to achieve?

Each machine in the cluster has its own clock. These will still have a certain amount of drift throughout the day.

So you can set up your own NTP server. (You can either run NTPd and sync to a known government clock) or you can spend money and buy an atomic clock for your servers or machine room.
(See http://www.atomic-clock.galleon.eu.com/ )

Then periodically throughout the day, via cron, have the machines in your machine room sync to the local NTP server.
This way all of your machines will have the same and correct time.

So this will sync the clocks to a degree, but then drift sets in.

Of course you also need to set up a machine to sync from... my vote would be the Name node. ;-)


On May 16, 2013, at 10:34 AM, Niels Basjes <[EMAIL PROTECTED]> wrote: