[Linux-cluster] ntpdate cman and random fence-ing

[Patrick Caulfield]

Ivan Pantovic wrote:
> 
> I have a straightforward question,
> 
> is it possible to screw-up cluster node(s) by issuing ntpdate while
> cluster is running?
> 
> I had random fencing of nodes (usually when load is low) and ... 
> recently I discovered that nodes are syncronised to ntp server using
> crontab and ntpdate.
> I know that ntpdate is all but not "gentle" and should be used only on
> system startup for "rude", prior to ntpd start, syncronisation.
> 
> I could go trough heartbeat routines and try to figure it out but just
> if someone already knows and is willing to share it?

It shouldn't be. cman uses the kernel jiffies for timing information rather than
actual wall-clock time.

Having said that I haven't tested this, and some of the userland code might be
more subject to clock variances. Mucking around with computer clocks too often
is usually a bad idea ;)

-- 

patrick