Stalled discovery runs

When a discovery run is scheduled for a particular scan range, the scheduled time is called its scan window. Scheduled discovery of the scan range can take place only in that open scan window.

Identifying stalled discovery runs

In either of the following situations, a discovery run can appear to be stalled:

The discovery run has not finished within its scheduled scan window. This scan is considered on hold. The run continues or restarts at the next scan window.
Discovering an endpoint requires additional discovery on another endpoint that is not currently in an open scan window. This scan is blocked.
When the scan window for the other endpoint opens, the endpoint is scanned, irrespective of whether the first endpoint is in an open scan window.

Restarting or continuing

At the next scheduled scan window, any runs that are on hold or blocked will continue or restart, depending on whether all endpoints have been started. The following happens:

The scan fails to finish in a scan window and all endpoints have not been started. The scan continues at the next window.
The scan fails to finish in a scan window and all endpoints have been started. The scan restarts at the next window.

Identifying locked and on-hold runs in the UI

The Currently Processing Runs tab of the Discovery Status window displays a red (on hold) notice if a run is on hold and a red (blocked) notice if a run is blocked.

To identify on-hold runs

Click anywhere in the row of the on hold run to display the Discovery Run page for that run. To check the scanning window:

From the Discovery Status page, click the Scheduled Runs tab.
The timing information for each scheduled run is shown in a table.

If you want to edit the discovery run, click its entry in the table to display the Edit an Existing Run dialog box.

To identify blocked runs

Click the (blocked) notice. A dialog box is displayed, showing the reason for the discovery run being blocked.

The blocked endpoint is shown, and the reason for it being blocked is given. In the preceding example, the blocked endpoint is 137.72.94.27, and it is blocked because the DiscoveryRuncommand.DiscoveryRuncommand pattern is attempting to access another endpoint (137.72.94.219) that is currently outside a scan window.