You can check the history of alerts issued by system monitoring on the Alert History page. The following figure shows this page.

Figure 11-22 Alert History page

The Alert History page lists alert issuance dates/times, alert messages, and alert codes. The alert type is indicated by a mark to the left of the issuance date/time. In the default setting, all alert history is output, but you can limit the type of alerts to be output. For details about how to output alerts to the Alert History page, see 11.8.4(2) Displaying alert messages on the Alert History page of Local System Viewer. For details about how to specify the types of alert to be output, see 11.8.2 Specifying system monitoring conditions.

On the Alert History page, you can perform the following operations:

• Sorting items in alert history
  In the list, click the column header to be used as the sorting key.
  
• Outputting alert history to a file
  By choosing File and then Output to CSV File, you can output alert history to a CSV file.
  
• Changing the number of alert history items to be saved
  Choose Edit and then Settings of Alert History. The Settings of Alert History window appears.
  

  Figure 11-23 Settings of Alert History dialog box

  

  Directly enter the number of items to be saved and press the Tab or Enter key, or use the slide bar to set the desired number. The default setting is 500 and the specifiable range is 1-500. The number that is set takes effect after you choose OK.
  
• Deleting alert history
  Choose Edit and then Clear Alert History. All accumulated alert history is deleted.