Cache limits are used to specify the maximum working size for all image cache volumes on the station—including web cache volumes, if Curator is used. You configure thresholds for each cache as the remaining number of hours of available space, and the system dynamically calculates a corresponding threshold equivalent percentage based on the current rate of incoming studies.
The system considers a threshold crossed when the rate of incoming studies fills the cache faster than the time specified. When this occurs, Autopilot deletes studies beginning with the lower-level threshold, according to the rules set on the Staging Rules tab. Autopilot does not delete studies until one of the threshold settings are crossed.
For example, an image cache has an amber threshold of 48 hours and a red threshold of 36 hours. As studies come in, the system determines that the cache volume does not have enough space to handle 48 hours of incoming studies. The amber threshold is reached and Autopilot begins deleting studies according to the specified rules. With the amber level deletions taking place, the system evaluates the required space for the next threshold level. If the cache does not have enough space to handle 36 hours of new studies, Autopilot implements the more aggressive deletion based on the red threshold rules.
 | Note: If the number of hours set for the Red Threshold is higher than the number of hours for the Amber Threshold, the red threshold is reached first, nullifying the amber threshold settings. |
To configure cache thresholds
On the Setup tab, click Autopilot Management.
From the Select Cached Station list, select the station.
Switch to the Configuration tab, if not selected.
In the Daytime and Nighttime fields, type each threshold’s number of hours remaining before cache space is filled (which will be used in the system’s dynamic calculations, based on the rate of incoming studies).
Daytime refers to the period of time between 6:00 and midnight (indicated by 0:00); Nighttime refers to the period of time between 0:01 and 5:59.
Click Save.
Thresholds
| Option | Required value |
|---|---|
| Amber Threshold | Number of hours remaining before cache space is filled based on current rate of incoming studies. |
| Red Threshold | Number of hours remaining before cache space is filled based on current rate of incoming studies. |
| Web Threshold | The threshold for the web cache. This option appears only if Curator is installed. |