Re: [ldm-users] 20090704: Level 2 radar issues from NWS CRH

On Sat, 4 Jul 2009, Tom Yoksas wrote:

So here's a request for LDM-6.7.2 and all future versions: That upon an
ldmadmin start, by default (though it can be turned off, in, say
ldmadmin-pl.conf, with a stern warning that this is a bad idea, but can
accomodate those having serious issues that they cannot rectify at the
time), it pings a NIST time server(s). If the server clock is off
more than 10 seconds, the LDM aborts and returns with a message that your
clock is X hours, minutes and seconds off, and needs to be adjusted.
Additionally, as a secondary option, it should check once a day at a time
you determine that it is less than 10 seconds (or under a minute) off. If
it is, the LDM can fire off an email message to root (or other user(s)),
letting you know the problem. I'll be happy to test it. A commercial
group of radar-display programs will exit with an error message if your
clock is off by 10 seconds or more. I really like that, too. If your
radar images or data are being delayed by clocks that are off, that's a
very bad thing(tm).

I am not sure that this is a good idea especially the LDM aborting part.
Even if one's clock is off, products will still flow eventually.

True, but they would recycle/circulate latent to other machines, and that's just bad all around because it causes more bandwidth to be consumed, regardless of whether or not the products are rejected.

the LDM exit/not start would preclude one from getting products altogether.

And therefore not cause any more problems downstream to you or to others. Or...if not a full stoppage, can a stern warning message be displayed, at least? "Hey, your system clock is more than 10 seconds off actual. You will cause problems to yourself and those downstream of you if this isn't fixed..."

What is better yet is the local LDM administrator reviewing the contents
of their LDM log files periodically.  When the clock on the upstream
is off in the future, products inserted in its LDM queue will trigger
log messages noting that the product is in the future.

True, but nothing like a real-time "heads up" to stave off problems.
Or, even warning messages in the LDM logs. That would be nice.

Gilbert Sebenste                                                     ********
(My opinions only!)                                                  ******
Staff Meteorologist, Northern Illinois University                      ****
E-mail: sebenste@xxxxxxxxxxxxxxxxxxxxx                                  ***
web:                                      **

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