https://zhuanlan.zhihu.com/p/440464163
https://access.redhat.com/documentation/en-us/red_hat_ceph_storage/3/html/troubleshooting_guide/troubleshooting-osds#slow-requests-and-requests-are-blocked
An OSD with slow requests is every OSD that is not able to service the I/O operations per second (IOPS) in the queue within the time defined by the osd_op_complaint_time parameter. By default, this parameter is set to 30 seconds.
请求慢的 OSD 是指在 osd_op_complaint_time 参数定义的时间内无法为队列中的每秒 I/O 操作 (IOPS) 提供服务的每个 OSD。默认情况下，此参数设置为 30 秒。
