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 Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated.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.
Hi Karl, There is no limit as to how far back you can request data from your upstream ldm. The only difficulty is that the arguments to rpc.ldmd are in seconds, so you'll have to calculate how many days worth of data you want in terms of seconds. (In the future we may add a suffix flag to the time argument so that you could specify times in other units.) There is a practical limit to how far back in time you can go - the time in seconds must fit in 31 bits (assuming the time is a signed value, which I think it is, and assuming you're using a 32 bit architecture). But, that shouldn't be a problem for you - 2**30 is 2,147,483,648 seconds, or over 24,000 days. Use the -m (max latency) flag to rpc.ldmd to do this. The -o (offset) flag refers to what data you want to request upon start up, and the -m flag refers to what data you are willing to accept. (You might find yourself accepting older data than you would request if your ldm falls behind for some reason.) By default, the offset will be the same as the max latency, which is what I assume you want, so using the -m flag should work. You'll probably want to edit the ldmadmin script to implement this change from the default set up. The only downside is that every time you get a new distribution you'll have to migrate your changes into the new ldmadmin script that came with the distribution. Good luck, and let me know if you have any further questions. Anne -- *************************************************** Anne Wilson UCAR Unidata Program address@hidden P.O. Box 3000 Boulder, CO 80307 ---------------------------------------------------- Unidata WWW server http://www.unidata.ucar.edu/ ****************************************************