device-mapper: ioctl: error adding target to table

device-mapper: table: 253:2: multipath: error getting device
device-mapper: ioctl: error adding target to table
有一路没有使用2个控制器就不存在多路径了，所有检测出错。

[root@ftp69 ~]# dmsetup -v status 查看Major, minor:
[root@ftp69 ~]# multipath -ll
[root@ftp69 ~]# cat /proc/partitions
[root@ftp69 ~]# dmsetup ls | sort

for i in `cat /proc/partitions | awk {'print $4'} |grep sd`; do echo "### $i: `scsi_id -g -u -s /block/$i`"; done

fdisk -l 2>/dev/null | grep ^Disk


multipath configurate
http://martincarstenbach.wordpress.com/2010/11/16/configuration-device-mapper-multipath-on-oel5-update-5/