我必须检查EC2机器是否已开启6个小时以上，因此我设置了CloudWatch警报，如果CPUUtilization > 0持续15分钟的24个周期内触发。问题是，即使机器使用较少，在关闭机器后，我也会收到类似以下内容的电子邮件。如您所见，阈值仅被越过了6/24点。但是我还是接到警报。任何线索，这是怎么回事？
Alarm Details:
- Name: Machine up
- Description: ATTENTION: the machine has been up for more than 6 hours.
- State Change: INSUFFICIENT_DATA -> ALARM
- Reason for State Change: Threshold Crossed: 6 out of the last 24 datapoints were greater than or equal to the threshold (0.0). The most recent datapoints which crossed the threshold: [4.2 (26/09/19 13:16:00), 4.8 (26/09/19 13:01:00), 6.933333333333334 (26/09/19 12:46:00), 4.0 (26/09/19 12:31:00), 24.4 (26/09/19 12:16:00)] (minimum 24 datapoints for OK -> ALARM transition).