如何排除主机与文件管理器之间的降级连接故障
适用场景
SAN 协议
问题描述
多路径(MPIO)软件允许主机维护LUN的多个路径。指向LUN所在NetApp节点的路径被视为"主动/优化"路径、而通过该节点的HA配对节点的路径被视为"主动/未优化"路径。具体术语可能因主机操作系统和多路径驱动程序而异。在某些情况下、可能会导致一个或多个路径无法访问或无法用于I/O根据不可用的路径、主机可能会出现性能下降、尤其是在没有其他"活动/优化"路径的情况下。
路径状态由当前拥有LUN的节点使用 ALOA确定。发生接管时、接管其配对节点LUN所有权的节点路径将变为"主动/优化"状态。
RedHat "multipath -ly"输出中的路径故障示例：
# multipath -ll
mpath0 (360a9800043346441464a44424c746e54)
[size=10 GB][features="1 queue_if_no_path"][hwhandler="0"]
_ round-robin 0 [prio=8][active]
_ 0:0:0:0 sda 8:0 [failed][faulty]
_ 1:0:0:0 sdi 8:128 [active][ready]
_ round-robin 0 [prio=2][enabled]
_ 0:0:1:0 sde 8:64 [active][ready]
_ 1:0:1:0 sdm 8:192 [active][ready]
RedHat "/var/log/messages "示例：Jun 22 15:55:54 rhel1 multipathd: Lun1: sdcr - tur checker reports path is down
Jun 22 15:55:54 rhel1 multipathd: checker failed path 69:240 in map Lun1
Jun 22 15:55:54 rhel1 multipathd: Lun1: remaining active paths: 3
Jun 22 15:55:54 rhel1 kernel: device-mapper: multipath: Failing path 69:240.
VMware vmkernel示例：2017-11-30T07:17:41.351Z cpu15:33143)WARNING: NMP: nmp_DeviceRequestFastDeviceProbe: NMP device "sym.029025256531353837" state in doubt; requested fast path state update...2017-11-30T07:17:41.351Z cpu15:33143)WARNING: ScsiPath: 4507: Path vmhba2:C0:T0:L55 is being removed
2017-11-30T07:17:41.351Z cpu15:33143)WARNING: ScsiPath: 6117: Remove path: vmhba2:C0:T0:L55
Windows的"系统事件日志"示例：Information 10/31/2017 4:39:33 PM mpio 46 None Path 1000001 was removed from \Device\MPIODisk2 due to a PnP event. The dump data contains the current number of paths.
Information 10/31/2017 4:39:33 PM ontapdsm 61070 None Path ID 01000001 was removed.
Warning 10/31/2017 4:39:33 PM ontapdsm 61054 None Path ID 01000001 has failed and 02000101 will be used instead.
Error 10/31/2017 4:39:33 PM ontapdsm 61142 None Path ID 01000001 has failed.
注：确切的日志条目可能会因操作系统版本以及多路径的配置方式而异。