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安装多路径软件（系统默认安装）
#第一：安装多路径软件yum -y install device-mapper device-mapper-multipath#第二：在CentOS7中启用多路径模块，mpathconf命令及相关模块加载（可以使用mpathconf -h查看用法） 使用 mpathconf 命令创建配置文件并启用多路径。若无需编辑该配置文件,可使用此命令启动多路径守护程序mpathconf --enablempathconf --with_module ympathconf --with_multipathd y#第三：在CentOS7中，启动multipathd服务及设置开机自启systemctl start multipathd.servicesystemctl enable multipathd.service注意：系统决定多路径设备的属性时,会先检查多路径设置,然后检查设备设置,最后才检查多路径系统默认设置
挂载iscsi设备，并记录iscsi设备的全球识别符wwid号
#第一：发现iscsiadm --mode discovery --type sendtargets --portal 192.168.1.40iscsiadm --mode discovery --type sendtargets --portal 192.168.1.50#第二：登录iscsiadm -d2 -m node -T iqn.1994-05.com.redhat:scst1 -p 192.168.1.40 --loginiscsiadm -d2 -m node -T iqn.1994-05.com.redhat:scst1 -p 192.168.1.50 --login#第三：查看磁盘（发现有两块相同大小容量的磁盘）fdisk -l#第四：查看并记录iscsi设备的wwid号multipath -l
编辑多路径软件DM-Multipath的配置文件，并重启多路径软件
#第一：修改DM配置文件vim /etc/multipath.confdefaults {user_friendly_names yesfind_multipaths yes
}multipaths {multipath {wwid 23237636464633731 #这是刚才记录的wwid号alias vda #配置显示别名path_grouping_policy multibuspath_selector "round-robin 0" #轮巡策略failback manualrr_weight prioritiesno_path_retry 5}
}blacklist {devnode "sda"
}#第二：reload多路径软件systemctl reload multipathd.service#第三：查看磁盘设备（发现出现了一块/dev/mapper/vda的磁盘）fdisk -l磁盘 /dev/mapper/vda：4293 MB, 4293693440 字节，8386120 个扇区
Units = 扇区 of 1 * 512 = 512 bytes
扇区大小(逻辑/物理)：512 字节 / 512 字节
I/O 大小(最小/最佳)：4096 字节 / 524288 字节
磁盘标签类型：dos
磁盘标识符：0x00032eb1#第四：分区，格式化，挂载使用#第五：测试多路径down eth0 测试是否磁盘可写down eth1，同时启用eth0 测试是否磁盘可写DM-Multipath的配置文件概述
defaults #DM Multipath 的常规默认设置。blacklist #不被视为多路径的具体设备列表。blacklist_exceptions #根据 blacklist 部分中的参数列出不在黑名单中的多路径设备multipaths #各个独立多路径设备的特性设置。这些数值覆盖了在配置文件的 defaults 和 devices 部分中指定的数值devices #各个存储控制器的设置。这些数值覆盖了在配置文件的 defaults 部分指定的数值。如果要使用不是默认支持的存储阵列,则可能需要为您的阵列创建 devices 子部分vim /etc/multipath.conf# This is a basic configuration file with some examples, for device mapper # multipath. # # For a complete list of the default configuration values, run either # multipath -t # or # multipathd show config # # For a list of configuration options with descriptions, see the multipath.conf # man page## By default, devices with vendor = "IBM" and product = "S/390.*" are ## blacklisted. To enable mulitpathing on these devies, uncomment the ## following lines. #blacklist_exceptions { # device { # vendor "IBM" # product "S/390.*" # } #}## Use user friendly names, instead of using WWIDs as names. defaults {user_friendly_names yesfind_multipaths yes } ## ## Here is an example of how to configure some standard options. ## # #defaults { # polling_interval 10 # path_selector "round-robin 0" # path_grouping_policy multibus # uid_attribute ID_SERIAL # prio alua # path_checker readsector0 # rr_min_io 100 # max_fds 8192 # rr_weight priorities # failback immediate # no_path_retry fail # user_friendly_names yes #} ## ## The wwid line in the following blacklist section is shown as an example ## of how to blacklist devices by wwid. The 2 devnode lines are the ## compiled in default blacklist. If you want to blacklist entire types ## of devices, such as all scsi devices, you should use a devnode line. ## However, if you want to blacklist specific devices, you should use ## a wwid line. Since there is no guarantee that a specific device will ## not change names on reboot (from /dev/sda to /dev/sdb for example) ## devnode lines are not recommended for blacklisting specific devices. ## #blacklist { # wwid 26353900f02796769 # devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*" # devnode "^hd[a-z]" #} #multipaths { # multipath { # wwid 3600508b4000156d700012000000b0000 # alias yellow # path_grouping_policy multibus # path_selector "round-robin 0" # failback manual # rr_weight priorities # no_path_retry 5 # } # multipath { # wwid 1DEC_____321816758474 # alias red # } #} #devices { # device { # vendor "COMPAQ " # product "HSV110 (C)COMPAQ" # path_grouping_policy multibus # path_checker readsector0 # path_selector "round-robin 0" # hardware_handler "0" # failback 15 # rr_weight priorities # no_path_retry queue # } # device { # vendor "COMPAQ " # product "MSA1000 " # path_grouping_policy multibus # } #}multipaths {multipath {wwid 23237636464633731alias vdapath_grouping_policy multibuspath_selector "round-robin 0"failback manualrr_weight prioritiesno_path_retry 5} }blacklist {devnode "sda" }
这是centos7 多路径设备支持官方文档
https://qiniu.wsfnk.com/Red_Hat_Enterprise_Linux-7-DM_Multipath-zh-CN.pdf