[ldm-users] Thoughts about LDM version 6.9.7


Why should I upgrade from LDM 6.6.X (or earlier)
or 6.8.1? My version works just fine, right?

I'm sure it does.

But there are several advantages to upgrading that
I have to share since I've been a beta-tester for it,
and have now used it operationally for a month and
a half now.

1. Notification of LDM issues. Over the years, I've seen many people say
"my LDM went down for a day or three, and I need data". I've been in that
boat many times before, when one of my lesser-used servers had a queue
corruption...and data was lost for days. Thankfully, I had other servers
to fall back on. But during a major weather event here at NIU, where I
work in part as a weather safety officer, I always had it in the back of
my mind of "what if the LDM crashes, and then a tornado warning is issued?
Or what if a feed suddenly goes down?" Usually, I resort in major weather events to having an ldmadmin watch feed going on one of my servers. But I
can't watch it all the time, obviously.

The crontab entries I passed along weeks ago solve that problem. Unless
I'm away from the servers for days on end, which is very rare, I can
be a lot less concerned that everything is working. A complete server
outage, such as a power down or hardware failure, may not be caught
(hopefully you have other alert systems in place for that). But if the
RAM exhausts itself if the hard drive goes down, you'll get messages
about the data not coming in, at least.

In my on-the-side job, I've used it to quickly track down issues, and keep the data flowing, and it's critical that we're up 24/7. One of the things I've appreciated as well is the "ldmadmin check" command. Recently, a network outage somehow caused the queue on one of the servers to become corrupted. But by the time I had logged in to fix it, ldmadmin watch "saw" that the queue was corrupted, shut down the LDM, remade the queue, and started it right back up again. And all was right with the world. Email notification of NOAAPort and other data outages when they happen
are extremely helpful to me. If something goes down, I need to know NOW.
But even if it's checking once an hour, or even once a day...it's
very helpful to do that, if your operations are of less critical
or of "passing interest".

2. Metrics. Want to see a 24 hour load average on a graph, and oodles
of other useful things? Type "plotMetrics", and away you go.
Queue size versus time, product count, LDM connections over time,
disk space, CPU modes, and age of the queue. For instance, I've learned
that for about 5 minutes around 14Z, the number of LDM connections drops
significantly, and then comes right back up. My investigation as to why
that was happening led to a tear-filled confession by Tom Yoksas on TMZ's
celebrity news show that he was unplugging the main UNIDATA IDD server to
plug in his electric shaver, and thankfully, that issue has been
resolved. (OK, really, I don't know what's happening with the brief LDM
connection dropouts. But it's on a daily basis, and I have NO idea why
that happens. Any suggestions greatly appreciated.)

3. Stability. 6.8.1 was rock stable, and 6.9.7 is too. Bugs, you say?
6.9.7...as in 7 revisions, you say? Not to worry. Those mainly install
issues have been fixed, and I haven't had serious issues with 6.9.X,
except in the betas. It "just works"...like it's supposed to.
A queue size issue has been fixed, and that was the only issue I was
struggling with a little. Otherwise, it has been fine.

So, if you have need for data, and need to know (or would like to
know) within a few hours that your NOAAport or NLDN or Level 2 feed is
down, and if your queue gets corrupted, for it to remake the queue
and restart automagically, install LDM 6.9.7. It's definitely worth your
time, certainly all of it that Steve Emmerson has poured into it over the
last several months.

Gilbert Sebenste                                                     ********
(My opinions only!)                                                  ******
Staff Meteorologist, Northern Illinois University                      ****
E-mail: sebenste@xxxxxxxxxxxxxxxxxxxxx                                  ***
web: http://weather.admin.niu.edu                                      **

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