我想要使用 2 个 HBA（每个 HBA 有两条路径）访问 FC-SAN 上的 3 个 LUN。系统启动时，一切似乎都很好，但过了一会儿，第二个 HBA 上的 sd* 设备消失了，我不知道为什么或如何在不重新启动的情况下找回它们。扫描 SCSI 总线仍然可以找到所有设备，但内核无法识别块设备。它是带有最新更新的 Red Hat 6.6。
相同的 LUN 在另一个系统上有 4 条路径可用，但在此系统上只有 2 条路径可用。
有人知道我可能错过了什么吗？
# lspci|grep Fibre
08:00.0 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)
08:00.1 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)
# lsscsi
...
[1:0:0:1] disk DataCore Virtual Disk DCS /dev/sdb
[1:0:0:2] disk DataCore Virtual Disk DCS /dev/sdc
[1:0:0:3] disk DataCore Virtual Disk DCS /dev/sdd
[1:0:1:1] disk DataCore Virtual Disk DCS /dev/sde
[1:0:1:2] disk DataCore Virtual Disk DCS /dev/sdf
[1:0:1:3] disk DataCore Virtual Disk DCS /dev/sdg
[2:0:0:1] disk DataCore Virtual Disk DCS -
[2:0:0:2] disk DataCore Virtual Disk DCS -
[2:0:0:3] disk DataCore Virtual Disk DCS -
[2:0:1:1] disk DataCore Virtual Disk DCS -
[2:0:1:2] disk DataCore Virtual Disk DCS -
[2:0:1:3] disk DataCore Virtual Disk DCS -
...
# rescan-scsi-bus.sh
...
0 new or changed device(s) found.
0 remapped or resized device(s) found.
0 device(s) removed.
事情发生时记录如下：
May 24 12:08:57 hostname kernel: sd 1:0:0:1: Parameters changed
May 24 12:08:57 hostname kernel: sd 1:0:1:3: Parameters changed
May 24 12:09:01 hostname kernel: sd 1:0:1:2: Parameters changed
May 24 12:09:24 hostname kernel: sd 1:0:1:1: Parameters changed
May 24 12:09:24 hostname kernel: sd 2:0:0:1: rejecting I/O to offline device
May 24 12:09:25 hostname multipathd: checker failed path 8:112 in map lun0
May 24 12:09:25 hostname multipathd: ora_data2: remaining active paths: 3
May 24 12:09:25 hostname multipathd: checker failed path 8:128 in map lun1
May 24 12:09:25 hostname multipathd: ora_acfs1: remaining active paths: 3
May 24 12:09:25 hostname multipathd: checker failed path 8:144 in map lun2
May 24 12:09:25 hostname multipathd: ora_acfs2: remaining active paths: 3
May 24 12:09:25 hostname multipathd: checker failed path 8:160 in map lun0
May 24 12:09:25 hostname multipathd: ora_data2: remaining active paths: 2
May 24 12:09:25 hostname multipathd: checker failed path 8:176 in map lun1
May 24 12:09:25 hostname multipathd: ora_acfs1: remaining active paths: 2
May 24 12:09:25 hostname multipathd: checker failed path 8:192 in map lun2
May 24 12:09:25 hostname multipathd: ora_acfs2: remaining active paths: 2
May 24 12:09:25 hostname kernel: device-mapper: multipath: Failing path 8:112.
May 24 12:09:25 hostname kernel: device-mapper: multipath: Failing path 8:128.
May 24 12:09:25 hostname kernel: device-mapper: multipath: Failing path 8:144.
May 24 12:09:25 hostname kernel: device-mapper: multipath: Failing path 8:160.
May 24 12:09:25 hostname kernel: device-mapper: multipath: Failing path 8:176.
May 24 12:09:25 hostname kernel: device-mapper: multipath: Failing path 8:192.
不幸的是，我无法访问 SAN 设备，但是有人告诉我没有发生任何变化。
我刚刚看到设备实际上已经消失了，但 2 小时后又回来了：
May 24 14:06:35 hostname kernel: scsi 2:0:1:1: Attached scsi generic sg9 type 0
May 24 14:06:35 hostname kernel: scsi 2:0:1:2: Attached scsi generic sg10 type 0
May 24 14:06:35 hostname kernel: scsi 2:0:1:3: Attached scsi generic sg11 type 0
May 24 14:06:37 hostname kernel: scsi 2:0:0:1: Attached scsi generic sg12 type 0
May 24 14:06:37 hostname kernel: scsi 2:0:0:2: Attached scsi generic sg13 type 0
May 24 14:06:37 hostname kernel: scsi 2:0:0:3: Attached scsi generic sg14 type 0
中间的 FC 交换机可能在那时被关闭了。当系统先前启动并且 sd 设备照常创建时，该行略有不同：
May 24 11:14:15 hostname kernel: sd 2:0:1:3: Attached scsi generic sg14 type 0
对阵
May 24 14:06:35 hostname kernel: scsi 2:0:1:1: Attached scsi generic sg9 type 0
它显示的是“scsi”而不是“sd”。