Hello all,

one test in Xymon, actually Hobbit 4.3.0, is performed hourly, thus in hobbitlaunch.cfg "INTERVAL 60m" is specified. The script delivers two totals of the last hour, which are collected in an RRA, type is GAUGE, and are displayed in Xymon. At first glance it works great.

However, the problem is that the displayed values (and thus the values stored in the RRA) differ from the measured values, and the difference is growing. It turns out that the difference is caused by interpolation of RRD: it computes the value at the last time-step using linear interpolation.

Additionally, the mean time between two successive invocations of the script is 3602 seconds. This implies that the correction caused by interpolation also grows.

If Xymon reports a time of test equal to the last time-step, RRD will not perform any interpolation. Is this possible?

Alternatively, if hobbitlaunch can start the script at a given time within an hour, like crontab, the difference due to interpolation can be minimized and will be stable. Is this possible?

Or is there a better way to have the measured values stored in the RRA?

TIA, Wim Nelis.

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