在日常工作中我们经常遇到配置存储的多路径聚合。多路径的目的是，当主机HBA卡、线缆、交换机或者存储设备的控制器故障等原因造成一条物理路径失效时,服务器可以将通过此物理路径的I/O转移到其他正常的物理路径上面,应用程序不会觉察到这种改变，从而提高系统的可用性，同时多路径冗余I/O也可以实现I/O的负载均衡，提高系统性能，但主要还是一种容错机制。下面是我使用Linux 自带的Multipath软件做多路径聚合的过程。

一、当存储映射新的LUN给服务器后，fdisk -l无法识别，需要使用下面命令，host1和host2是HBA卡的实际文件夹路径(/sys/class/host/host*)

识别命令：

echo 1 > /sys/class/fc_host/host1/issue_lip

echo 1 > /sys/class/fc_host/host8/issue_lip

echo "- - -" > /sys/class/scsi_host/host1/scan

echo "- - -" > /sys/class/scsi_host/host8/scan

使用fdisk -l可以看到有四个磁盘。实际上这只是磁盘的路径而不是磁盘。

二、识别到的/dev/sd*并不是磁盘，而是路径，需要使用多路径软件multipath，将路径虚拟为一个磁盘。

1、安装多路径软件

yum -y install device-mapper-multipath

配置开机启动

systemctl enable multipathd.service

拷贝配置文件

cp /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf /etc/

2、查看新映射LUN的wwid

本地磁盘：

[root@ysyk_resources multipath]# /usr/lib/udev/scsi_id --whitelist --device=/dev/sda

36d4ae520a2229700179cc3741957982c

LUN路径：

[root@ysyk_resources multipath]# /usr/lib/udev/scsi_id --whitelist --device=/dev/sdb

36000d3100152fa000000000000000004

[root@ysyk_resources multipath]# /usr/lib/udev/scsi_id --whitelist --device=/dev/sdc

36000d3100152fa000000000000000004

[root@ysyk_resources multipath]# /usr/lib/udev/scsi_id --whitelist --device=/dev/sdd

36000d3100152fa000000000000000004

[root@ysyk_resources multipath]# /usr/lib/udev/scsi_id --whitelist --device=/dev/sde

36000d3100152fa000000000000000004

[root@ysyk_resources multipath]#

3、编辑multipath.conf

defaults {

user_friendly_names yes

find_multipaths yes

}

#

defaults {

user_friendly_names yes

polling_interval 10

checker_timeout 120

queue_without_daemon no

flush_on_last_del yes

}

##黑名单标记所有本地磁盘，multipaths标记所有路径

blacklist {

wwid 36d4ae520a2229700179cc3741957982c

}

multipaths {

multipath {

wwid 36000d3100152fa000000000000000004

alias data01

}

multipath {

#如果有其他LUN再添加即可

}

}

#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

# }

#}

4、查看多路径

[root@ysyk_resources ~]# systemctl restart multipathd

[root@ysyk_resources multipath]# multipath -ll

May 14 15:25:16 | /etc/multipath.conf line 6, duplicate keyword: defaults

data01 (36000d3100152fa000000000000000004) dm-1 COMPELNT,Compellent Vol

size=20T features='1 queue_if_no_path' hwhandler='0' wp=rw

`-+- policy='service-time 0' prio=1 status=active

|- 1:0:19:1 sdb 8:16 active ready running

|- 1:0:23:1 sdc 8:32 active ready running

|- 8:0:21:1 sde 8:64 active ready running

`- 8:0:23:1 sdd 8:48 active ready running

[root@ysyk_resources multipath]#

三、格式化分区：

[root@ysyk_resources ~]# mkfs.ext4 -T largefile /dev/mapper/data01

mke2fs 1.42.9 (28-Dec-2013)

Discarding device blocks: done

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

Stride=512 blocks, Stripe width=512 blocks

20971520 inodes, 5368709120 blocks

268435456 blocks (5.00%) reserved for the super user

First data block=0

163840 block groups

32768 blocks per group, 32768 fragments per group

128 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,

4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968,

102400000, 214990848, 512000000, 550731776, 644972544, 1934917632,

2560000000, 3855122432

Allocating group tables: done

Writing inode tables: done

Creating journal (32768 blocks): done

Writing superblocks and filesystem accounting information: done

四、查看uuid

[root@ysyk_resources ~]# blkid

/dev/sda1: UUID="a857b07d-bb4f-42eb-95e9-f205fd39350f" TYPE="ext4"

/dev/sda2: UUID="3d73a9d0-c4db-4e4c-8b5d-2b78306fe1d1" TYPE="swap"

/dev/sda3: UUID="pezhpr-9joV-Rt6H-Jl1s-a2bk-Kja8-JSSd8L" TYPE="LVM2_member"

/dev/mapper/cl00-lv: UUID="3d0980f8-26ec-4e36-a4df-b68372922cc7" TYPE="xfs"

/dev/mapper/data01: UUID="c4182d79-93a1-49bd-b4aa-dba4517a4d42" TYPE="ext4"

[root@ysyk_resources ~]#

五、挂载磁盘

[root@ysyk_resources ~]# vim /etc/fstab

#

# /etc/fstab

# Created by anaconda on Wed May 9 12:14:28 2018

#

# Accessible filesystems, by reference, are maintained under '/dev/disk'

# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info

#

/dev/mapper/cl00-lv / xfs defaults 0 0

UUID=a857b07d-bb4f-42eb-95e9-f205fd39350f /boot ext4 defaults 1 2

UUID=3d73a9d0-c4db-4e4c-8b5d-2b78306fe1d1 swap swap defaults 0 0

UUID=c4182d79-93a1-49bd-b4aa-dba4517a4d42 /opt/data01 ext4 defaults 0 0

~

[root@ysyk_resources ~]# mount -a

[root@ysyk_resources ~]# df -h

Filesystem Size Used Avail Use% Mounted on

/dev/mapper/cl00-lv 550G 5.6G 545G 2% /

devtmpfs 32G 0 32G 0% /dev

tmpfs 32G 144K 32G 1% /dev/shm

tmpfs 32G 18M 32G 1% /run

tmpfs 32G 0 32G 0% /sys/fs/cgroup

/dev/sda1 477M 144M 304M 33% /boot

tmpfs 6.3G 24K 6.3G 1% /run/user/0

/dev/mapper/data01 20T 20K 19T 1% /opt/data01

[root@ysyk_resources ~]#