No, it's an obvious data error. The same drives reappear in future months. Pause and look at 2013-08-01 through 2013-11-01, or 2015-09-01 through 2016-01-01 to

No, it's an obvious data error. The same drives reappear in future months. Pause and look at 2013-08-01 through 2013-11-01, or 2015-09-01 through 2016-01-01 to confirm this.