And why do we need to check it one more time after 24 hours? After deleting the range the first time, if coincidentally PD is trying to move a Region or something, some data may still appear in the range. So check it one more time after a proper time to greatly reduce the possibility.
IO 打满可能是由 compaction 导致：
After deleting all files in a very-large range, it may trigger RocksDB’s compaction (even it is not really needed) and even cause stalling.