LDM Tips

This webpage contains "best practice" advice on the LDM.

• Size the product-queue (LDM registry parameters "/queue/size" and "/queue/slots") sufficiently large so that the age of the oldest product in the queue is greater than the maximum latency parameter ("/server/max-latency"). Once you get close enough, set the "/reconciliation-mode" parameter to "increase queue". Use the "ldmadmin plotmetrics" command to help you determine when you're close.
• Have sufficient physical memory on the LDM computer to allow the product-queue to be completely contained in memory.
• When practicable, have two REQUEST entries for the same data to two, different, upstream LDM-s.
• Execute data-product ingesters via EXEC entries in the LDM configuration-file so that the LDM process-group will be signaled when a new product is inserted.
• Consider splitting a large-volume REQUEST entry in the LDM configuration-file, ldmd.conf, into multiple, smaller, disjoint entries. More information.
• Favor doing your local processing of data-products by pqact on a computer that's not relaying data.
• If you process a lot of data-products locally on the computer via pqact, then you should consider having multiple EXEC pqact... entries in your LDM configuration-file -- each using a different, feedtype-specific pqact configuration-file and having a different -f feedtype option. This will reduce the size of each pqact's configuration-file and, consequently, the time spent attempting to find a matching entry.