The collection interval for DataSources and ConfigSources defines how frequently the device is polled for data. This value is controlled by the 'Collect every' setting in the LogicModule definition.
Collection Interval Best Practices
The Collection Schedule is typically set to an interval appropriate to the data being checked.
Instrumentation that changes quickly (CPU) or are important to alert on quickly (ping loss) have a short polling cycle such as 1 minute. Systems that can tolerate a longer period between alerts, or change less frequently (drive loss in a RAID system, disk utilization ) have a longer poll cycle -- maybe 5 minutes.
Longer poll cycles impose less load on the server being monitored, the Collector, and the LogicMonitor platform.
Changing the Collection Interval
Once a LogicModule has been applied to one or more devices and monitored instances are created for those devices, the underlying data storage is created with some dependency on the collection interval. In order to minimize data loss, this underlying data storage isn't updated when you change the collection interval for the LogicModule. This has a few impacts on how data is stored and displayed:
- If the collection interval is decreased (e.g. the collection interval is reduced from 15 minutes to 1 minute), then the data is collected and evaluated for alerts on the new schedule - but only stored (and hence graphed) with the old schedule. Given in this case we are collecting 15 samples where we previously only collected 1 sample, the average of the 15 samples is stored, updated every 15 minutes, and this is all that can be seen on the graphs (no matter how much you zoom in).
- If the collection interval is increased (e.g. the collection interval is increased from 1 minute to 15 minutes), then the data is collected and evaluated for alerts on the new schedule, and again stored on the old schedule.
You can see the collection interval with which the underlying datastore was created by downloading the data from a graph. This will show the update periods that the instance was created with, and with which it expects data to be inserted.
Remember that the collection interval established in the LogicModule definition represents the default setting for a LogicModule. This value can be overridden from the properties of a device or device group, as discussed in Can I customize data collection intervals for a device?.