出现“rport-1:0-0: blocked FC remote port time out: saving binding”报错

Issue

• 系统的 /var/log/messages、/var/log/dmesg 或 vmcore 中包括以下事件，这意味着在主机的 HBA 和存储设备间丢掉了 FC 路径：

{RHEL6,7}
Jun  5 23:46:53 HOST kernel:  rport-1:0-0: blocked FC remote port time out: removing target and saving binding
Jun  5 23:46:53 HOST kernel:  rport-1:0-1: blocked FC remote port time out: removing target and saving binding

{RHEL5}
Jun  5 23:46:53 HOST kernel:  rport-1:0-0: blocked FC remote port time out: saving binding
Jun  5 23:46:53 HOST kernel:  rport-1:0-1: blocked FC remote port time out: saving binding

-如果设置了 fc_remove_on_dev_loss 选项-
Jun  5 23:46:53 HOST kernel:  rport-1:0-0: blocked FC remote port time out: removing target and saving binding
Jun  5 23:46:53 HOST kernel:  rport-1:0-1: blocked FC remote port time out: removing target and saving binding

• 匹配 multipath 的设备路径有故障，使用 multipath -ll 可显示发生故障的路径:

360060e80056204000000620400000085 dm-1 HP,OPEN-V
[size=30G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=2][active]
 \_ 2:0:0:1 sdb 8:16  [active][ready]
 \_ 3:0:0:1 sdd 8:48  [failed][ready]   <---

• 在 /var/log/messages中发现下述日志，这可能是问题的根源或可能对解决问题有所帮助:

Jan 20 15:54:20 HOST kernel: qla2xxx 0000:0f:00.1: LOOP DOWN detected (2 3 0).
Jan 20 15:54:36 HOST kernel:  rport-3:0-0: blocked FC remote port time out: saving binding
Jan 20 15:54:36 HOST kernel: sd 3:0:0:1: SCSI error: return code = 0x00010000
Jan 20 15:54:36 HOST kernel: end_request: I/O error, dev sdd, sector 593496
Jan 20 15:54:36 HOST kernel: device-mapper: multipath: Failing path 8:48.

• 在日志中出现 blocked FC remote port time out: saving binding，Ext4 文件系统以只读方式挂载造成系统挂起。
• 服务器内核 panic，vmcore 中包含 blocked FC remote port 错误日志， 什么原因导致这个问题？