Linux multipath与SCSI ID

Scsi_id命令包含在udev程序包中，可以在multipath.conf中配置该程序来获取scsi设备的SCSI ID。通过SCSI ID，便可以判断多个路径对应了同一设备。这个是多路径实现的关键。scsi_id是通过sg驱动，向设备发送EVPD page80或page83 的inquery命令来查询scsi设备的标识。但一些设备并不支持EVPD 的inquery命令，所以他们无法被用来生成multipath设备。如果这样，据说可以手工改写scsi_id，为不能提供scsi设备标识的设备虚拟一个标识符，并输出到标准输出，但是改写SCSI ID的方法不详。

multipath程序在创建multipath设备时，会调用scsi_id，从其标准输出中获得该设备的scsi id。

 

1. 1.       几个查看SCSI设备详细信息的命令
l  cat /proc/scsi/scsi
[root@centos-i2lb]# cat /proc/scsi/scsi
Attacheddevices:
Host: scsi1Channel: 00 Id: 00 Lun: 00
  Vendor: NECVMWar Model: VMware IDE CDR10 Rev:1.00
  Type:  CD-ROM                          ANSI  SCSI revision: 05
Host: scsi2Channel: 00 Id: 00 Lun: 00
  Vendor: VMware,  Model: VMware Virtual S Rev: 1.0 
  Type:  Direct-Access                   ANSI  SCSI revision: 02
Host: scsi6Channel: 00 Id: 00 Lun: 00
  Vendor: IET      Model: Controller       Rev: 0001
  Type:  RAID                            ANSI  SCSI revision: 05
Host: scsi5Channel: 00 Id: 00 Lun: 00
  Vendor: IET      Model: Controller       Rev: 0001
  Type:  RAID                             ANSI SCSI revision: 05
Host: scsi5Channel: 00 Id: 00 Lun: 01
  Vendor: lb       Model: lb_iscsi         Rev: 01  
  Type:  Direct-Access                   ANSI  SCSI revision: 05
Host: scsi6Channel: 00 Id: 00 Lun: 01
  Vendor: lb       Model: lb_iscsi         Rev: 01  
  Type:  Direct-Access                   ANSI  SCSI revision: 05
• Lsscsi工具（需要安装）
[root@centos-i2lb]# lsscsi -v 
[1:0:0:0]    cd/dvd NECVMWar VMware IDE CDR10 1.00 /dev/sr0 
  dir: /sys/bus/scsi/devices/1:0:0:0 [/sys/devices/pci0000:00/0000:00:07.1/host1/target1:0:0/1:0:0:0]
[2:0:0:0]    disk   VMware,  VMware Virtual S 1.0   /dev/sda 
  dir: /sys/bus/scsi/devices/2:0:0:0 [/sys/devices/pci0000:00/0000:00:10.0/host2/target2:0:0/2:0:0:0]
[5:0:0:0]    storage IET      Controller       0001 -       
  dir: /sys/bus/scsi/devices/5:0:0:0 [/sys/devices/platform/host5/session3/target5:0:0/5:0:0:0]
[5:0:0:1]    disk   lb       lb_iscsi         01   /dev/sdb 
  dir: /sys/bus/scsi/devices/5:0:0:1 [/sys/devices/platform/host5/session3/target5:0:0/5:0:0:1]
[6:0:0:0]    storage IET      Controller       0001 -       
  dir: /sys/bus/scsi/devices/6:0:0:0 [/sys/devices/platform/host6/session4/target6:0:0/6:0:0:0]
[6:0:0:1]    disk   lb       lb_iscsi         01   /dev/sdc 
  dir: /sys/bus/scsi/devices/6:0:0:1 [/sys/devices/platform/host6/session4/target6:0:0/6:0:0:1]
 
 
 
l  ls –rtl /dev/disk/by-id
[root@centos-i2lb]# ls -rtl /dev/disk/by-id
total 0
lrwxrwxrwx. 1root root  9 Apr  7 13:16ata-VMware_Virtual_IDE_CDROM_Drive_10000000000000000001 -> ../../sr0
lrwxrwxrwx. 1root root 10 Apr  7 13:16lvm-pv-uuid-K3FudW-pVbU-3CxO-vYbz-JQgt-7cMD-trWZfc -> ../../sda2
lrwxrwxrwx. 1root root 10 Apr  7 13:16dm-uuid-LVM-6OQeAXlfx14VazFp21YfwgbtSE3P0IH1BMNhZdogpE93EoKvCxT3KZcCAqVmjG6M-> ../../dm-1
lrwxrwxrwx. 1root root 10 Apr  7 13:16dm-name-vg_centosi2-lv_swap -> ../../dm-1
lrwxrwxrwx. 1root root 10 Apr  7 13:16dm-uuid-LVM-6OQeAXlfx14VazFp21YfwgbtSE3P0IH129JpYlBs33F2gS64l2eNyeeIasmtvu2O-> ../../dm-0
lrwxrwxrwx. 1root root 10 Apr  7 13:16dm-name-vg_centosi2-lv_root -> ../../dm-0
lrwxrwxrwx. 1root root  9 Apr  7 13:28 scsi-1IET_00010001 -> ../../sdb
lrwxrwxrwx. 1root root 10 Apr  7 13:28dm-uuid-mpath-1IET\x20\x20\x20\x20\x2000010001 -> ../../dm-2
lrwxrwxrwx. 1root root 10 Apr  7 13:28 dm-name-yellow-> ../../dm-2
lrwxrwxrwx. 1root root 10 Apr  7 13:28dm-uuid-part1-mpath-1IET\x20\x20\x20\x20\x2000010001 -> ../../dm-3
lrwxrwxrwx. 1root root 10 Apr  7 13:28dm-name-yellowp1 -> ../../dm-3
• ls –rtl /dev/disk/by-id
[root@centos-i2lb]# ls -rtl /dev/disk/by-path
total 0
lrwxrwxrwx. 1root root  9 Apr  7 13:16 pci-0000:00:10.0-scsi-0:0:0:0 ->../../sda
lrwxrwxrwx. 1root root  9 Apr  7 13:16 pci-0000:00:07.1-scsi-1:0:0:0 ->../../sr0
lrwxrwxrwx. 1root root 10 Apr  7 13:16pci-0000:00:10.0-scsi-0:0:0:0-part2 -> ../../sda2
lrwxrwxrwx. 1root root 10 Apr  7 13:16pci-0000:00:10.0-scsi-0:0:0:0-part1 -> ../../sda1
lrwxrwxrwx. 1root root  9 Apr  7 13:28ip-192.168.136.101:3260-iscsi-iqn.2017-03.centos-i1:target1-lun-1 ->../../sdc
lrwxrwxrwx. 1root root  9 Apr  7 13:28ip-192.168.20.101:3260-iscsi-iqn.2017-03.centos-i1:target1-lun-1 ->../../sdb
1. 2.       Linustorvalds关于使用scsiid的争论

https://blog.51cto.com/leesbing/1914346