This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
Anne Wilson wrote:
Joe Van Andel wrote:With LDM 5.1.4 on Redhat 7.2, we've seen instances where data stops flowing from 1 site, while still flowing from other sites. For example, yesterday, syrah.atd.ucar.edu stopped getting our NEXRD2 feed from iita.rap.ucar.edu, even though the network was up and iita.rap.ucar.edu was still up. At the same time, syrah.atd.ucar.edu was still receiving S-Pol gridded radar data, via linus.atd.ucar.edu The data feed resumed once we restarted ldm on syrah. Clearly, we don't want to have to monitor whether our data is flowing and manually restart ldm if the data isn't arriving. Has anyone else seen network error conditions that can only be resolved by restarting ldm? -- Joe VanAndel National Center for Atmospheric Research http://www.atd.ucar.edu/~vanandel/ Internet: address@hiddenHi Joe, Was there anything in your log or iita's log when this occurred? It would show if there was an actual disconnect. I'm wondering if this might be related to the work the UCAR network people are doing these days in upgrading routers, although I don't know of anything that happened specifically yesterday...
I don't have access to iita's log - and didn't see anything in my log.
Has this happened more than once?
Yes.
Regarding RH 7.2 vs. 7.3, perhaps Gilbert is right. We've not experienced this problem on our own 7.2 machine, but we haven't pushed it much either. We did, however, have another site that had trouble with 7.2 that was fixed with going to 7.3. Are you considering upgrading the OS?
Sure, but since we're in the middle of the project, and syrah.atd.ucar.edu is a key machine, nobody will be very enthusiastic about taking the machine down to upgrade it.
Also, when this occurs you could run 'netstat | grep iita' on syrah to see what state syrah thinks the connection is in.
Good idea, we'll try this if it happens again.
I'm sorry that I can't offer much help on this one. A band-aid would be a script that tracked input files (if you're actually filing the data) that sends an email if there's a gap. Let me know if you'd like something like that, although that merely shifts the problem from monitoring a data stream to monitoring email. If this happens again and I'm around I would be happy to log in look around if you would like me to.
Thanks, I appreciate the offer.
Anne
-- Joe VanAndel National Center for Atmospheric Research http://www.atd.ucar.edu/~vanandel/ Internet: address@hidden