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Resolution and Data Retention

Note

This information applies to you only if your organization’s subscription plan is based on the number of hosts or metrics that SignalFx is monitoring for you. If your organization’s usage is based on the rate at which you are sending datapoints to SignalFx (DPM), see Data Resolution and Retention (DPM plans only).

In SignalFx, the term “resolution” can refer to data collection intervals (data resolution) or intervals at which datapoints are displayed on a chart (chart resolution).

Data resolution

Datapoints are typically sent to SignalFx at a regular interval, e.g. once every 10 seconds. We refer to this interval as the native resolution of a time series.

When plotting a graph or evaluating an analytical expression, the SignalFx service first needs to determine the data resolution of the metrics on the chart. The data resolution determines the precision and quality of the chart that you ultimately see.

For data coming in more often than every 10s, the data resolution depends on whether the datapoint was specified as high-resolution when it was sent to SignalFx.

  • If a datapoint is specified as high resolution when it is sent to SignalFx, we will consider its native resolution (as fine as one second) as the data resolution. In other words, if you are sending in 1s data, graphs and detectors can display or analyze the data at 1‑second intervals. (For more information on designating data as high-resolution, contact support@signalfx.com.)
  • For standard resolution data, we will consider data resolution to be either the native resolution or 10s resolution, whichever is coarser. That is, if you are sending in 1s data, the data resolution will be considered 10s; we will roll up the 1s datapoints to 10s, and graphs and detectors can display or analyze the values at 10‑second intervals. If you are sending in data at a rate >= every 10 seconds, we will consider that rate to be the data resolution.

Chart resolution

When rendering charts, SignalFx defaults to a resolution that is based on the time range of the chart. In general, the shorter the time range, the finer the resolution, and the greater the likelihood that the chart resolution will be the same as the data resolution.

Conversely, the longer the time range, the coarser the resolution, and the greater the likelihood that the chart resolution will differ from the data resolution. SignalFx ensures accuracy for such a chart through the use of rollups.

For example, let’s say you are sending in CPU utilization measurements for a cluster of hosts every 10 seconds, but you want to chart the average CPU utilization across the cluster over a two-week period. In this case, it doesn’t make sense to use the data resolution, as the sheer number of 10-second intervals in a two-week period (14 x 24 x 60 x 6 = 120,960) would not be viewable on most physical displays.

Instead, SignalFx will roll up the data to display it at a resolution that will allow all the data to fit in the chart. For example, a chart for a two-week period might roll up data to a 1‑hour resolution.

The chart resolution of a time series is also affected by its age and corresponding data retention policy. For example, under SignalFx’s default data rollup and retention policy, a 1-year time shifted version of a 10s-resolution time series will have a resolution of 1 hour, and it is this 1-hour resolution that will be used in a chart plotting both the current time series and its time-shifted cousin.

You can use the chart resolution selector at the top right of a dashboard or chart to increase or decrease the resolution. For more information, see Chart display resolution.

Plots involving different resolutions

Many charts contain more than one time series, and those time series may have different resolutions. SignalFx chooses one resolution per chart, so in these cases we will choose the coarsest resolution. Doing so ‘lines up’ the datapoints for plotting or analytical purposes.

User-selected minimum resolution

On the Chart Options tab, you have the option of selecting a minimum resolution for a chart: Auto, one second (1s), five seconds (5s), ten seconds (10s), thirty seconds (30s), one minute (1m) or one hour (1h). The value you select specifies the minimum interval for which SignalFx should roll up values to display a datapoint on the chart. For more information, see Minimum resolution.

Resolution and data retention policies

Data is retained at different resolutions depending on how long ago the data was received, the subscription plan that was in effect when the data arrived at SignalFx, and whether the datapoint was specified as high resolution when it was sent to SignalFx. (For more information on high-resolution metrics, contact support@signalfx.com.)

  • High resolution metrics can be stored at a resolution as fine as 1 second.
  • Standard resolution metrics can be stored at a resolution as fine as 10 seconds.
Resolution Standard plan Enterprise or Custom plan
1 second 8 days 3 months (96 days)
10 seconds 8 days 3 months (96 days)
1 minute 13 months (384 days) 13 months (384 days)