Multipath相关软件介绍

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1. device-mapper-multipath

　　即multipath-tools，主要提供multipathd和multipath等工具和 multipath.conf等配置文件。这些工具通过device mapper的ioctr的接口创建和配置multipath，设备创建的多路径设备映射会在/dev /mapper中。

2. device-mapper

　　主要包括两大部分：内核部分和用户部分。内核部分主要由device mapper核心（dm.ko）和一些target driver（md-multipath.ko）。核心完成设备的映射，而target根据映射关系和自身特点具体处理从mappered device 下来的i/o。同时，在核心部分，提供了一个接口，用户通过ioctr可和内核部分通信，以指导内核驱动的行为，比如如何创建mappered device，这些divece的属性等。linux device mapper的用户空间部分主要包括device-mapper这个包。其中包括dmsetup工具和一些帮助创建和配置mappered device的库。这些库主要抽象，封装了与ioctr通信的接口，以便方便创建和配置mappered device。multipath-tool的程序中就需要调用这些库

3. dm-multipath.ko和dm.ko：dm.ko是device mapper驱动。它是实现multipath的基础。dm-multipath其实是dm的一个target驱动。

https://www.cnblogs.com/jianqian ... /09/01/2162574.html

AIX

http://blog.163.com/herod_xiao/blog/static/871883992011819112227689/

1. 检查multipath模块，如果没有相关模块就说明没有安装相关软件包

lsmod | grep dm_multipath

yum -y install device-mapper device-mapper-multipath

2. 加载相关模块

modprobe dm-multipath

modprobe dm-round-robin

3. 生成multipath配置文件，并配置

/sbin/mpathconf --enable

配置multipath.conf文件

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4. 启动multipath服务

service multipathd start

chkcofig multipathd on

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[root@tyhr ~]# multipath -llmpathc (36005076801820709e000000000000087) dm-3 IBM,2145size=300G features='1 queue_if_no_path' hwhandler='0' wp=rw`-+- policy='round-robin 0' prio=1 status=active  |- 4:0:0:1 sdc 8:32  active ready running  |- 4:0:2:1 sde 8:64  active ready running  |- 5:0:2:1 sdg 8:96  active ready running  `- 5:0:4:1 sdi 8:128 active ready runningmpathb (36005076801820709e000000000000086) dm-2 IBM,2145size=100G features='1 queue_if_no_path' hwhandler='0' wp=rw`-+- policy='round-robin 0' prio=1 status=active  |- 4:0:0:0 sdb 8:16  active ready running  |- 4:0:2:0 sdd 8:48  active ready running  |- 5:0:2:0 sdf 8:80  active ready running  `- 5:0:4:0 sdh 8:112 active ready running[backcolor=rgb(245, 245, 245) !important][url=][/url]
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如果完成配置后，不能使用multipath -ll查看到任何多路径信息，就需要手工重新扫描HBA信息

一般新增LUN映射给主机后，系统无法直接更新挂载的存储盘，需要重新扫描。

# cd /sys/class/scsi_host/host4/# echo '- - - ' > scan或echo "1" > /sys/class/fc_host/host/issue_lip  //某些存储或系统没有scan文件，可以通issue_lip文件识别

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RHEL5.x 操作系统，新增multipath后，能够识别磁盘，但是通过fdisk分区后，不能显示分区信息（/dev/mapper/dm-app 磁盘不显示/dev/mapper/dm-appp1）。partprob无报错但是没有效果。fdisk w保存后有报错：

WARNING: Re-reading the partition table failed with error 22: Invalid argument.

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Run "kpartx -a" after FDISK is completed to add all partition mappings on the newly-created multipath device " a* x( M6 K2 Q4 J   K% m  l4 P5 e% T- L $ J$ X$ N" }) M3 @ [root@TYEDI1 host4]# ls -l /dev/mapper/dm-* brw-rw---- 1 root disk 253, 0 Jan 21 22:59 /dev/mapper/dm-app # d3 p1 E7 M1 Y+ E# l( _' r brw-rw---- 1 root disk 253, 2 Jan 21 22:35 /dev/mapper/dm-arch brw-rw---- 1 root disk 253, 1 Jan 21 22:52 /dev/mapper/dm-db 1 ^1 W! N0 ^6 H) F& ? [root@TYEDI1 host4]# kpartx -a /dev/mapper/dm-app * N6 c  Q0 L: _. r; M0 z [root@TYEDI1 host4]# ls -l /dev/mapper/dm-* brw-rw---- 1 root disk 253, 0 Jan 21 22:59 /dev/mapper/dm-app brw-rw---- 1 root disk 253, 3 Jan 21 23:01 /dev/mapper/dm-app1 brw-rw---- 1 root disk 253, 2 Jan 21 22:35 /dev/mapper/dm-arch , m5 t) Q. ]/ D9 F2 ~ brw-rw---- 1 root disk 253, 1 Jan 21 22:52 /dev/mapper/dm-db # H7 l; E7 K5 |, w) T : Z# `5 B( \) a, v, F- O

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其他配置：

1. udev绑定权限

RHEL6.5，对于multipath的权限，手工去修改几秒后会变回root。所以需要使用udev去绑定好权限。

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4 b  q  |  @6 z( ]; P1 p& A2 z1)搜索对应的配置文件模板：[root@jyrac1 ~]# find / -name 12-*/usr/share/doc/device-mapper-1.02.79/12-dm-permissions.rules\
2)根据模板新增12-dm-permissions.rules文件在/etc/udev/rules.d/下面：vi /etc/udev/rules.d/12-dm-permissions.rules# MULTIPATH DEVICES## Set permissions for all multipath devicesENV{DM_UUID}=="mpath-?*", OWNER:="grid", GROUP:="asmadmin", MODE:="660"# Set permissions for first two partitions created on a multipath device (and detected by kpartx)# ENV{DM_UUID}=="part[1-2]-mpath-?*", OWNER:="root", GROUP:="root", MODE:="660"3)查看多路径对应的底层dm设备：[root@jyrac2 rules.d]# ls -lh /dev/dm*brw-rw---- 1 root disk 253, 0 Jul 19 16:40 /dev/dm-0brw-rw---- 1 root disk 253, 1 Jul 19 16:40 /dev/dm-1brw-rw---- 1 root disk 253, 2 Jul 19 21:20 /dev/dm-2brw-rw---- 1 root disk 253, 3 Jul 19 21:20 /dev/dm-34)启动start_udev[root@jyrac2 rules.d]# start_udev Starting udev: [  OK  ]5)查看权限：[root@jyrac2 rules.d]# ls -lh /dev/dm*brw-rw---- 1 root disk     253, 0 Jul 19 21:35 /dev/dm-0brw-rw---- 1 root disk     253, 1 Jul 19 21:35 /dev/dm-1brw-rw---- 1 grid asmadmin 253, 2 Jul 19 21:35 /dev/dm-2brw-rw---- 1 grid asmadmin 253, 3 Jul 19 21:35 /dev/dm-36)等30s后再查，权限固定：[root@jyrac2 rules.d]# ls -lh /dev/dm*brw-rw---- 1 root disk     253, 0 Jul 19 21:35 /dev/dm-0brw-rw---- 1 root disk     253, 1 Jul 19 21:35 /dev/dm-1brw-rw---- 1 grid asmadmin 253, 2 Jul 19 21:35 /dev/dm-2brw-rw---- 1 grid asmadmin 253, 3 Jul 19 21:35 /dev/dm-3[backcolor=rgb(245, 245, 245) !important][url=][/url]
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可以使用lsscsi查看识别的磁盘信息：

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- H( V; h6 }2 V6 S2 Z5 N: _5 x2 H# q[root@tyhr ~]#  lsscsi [0:0:0:0]    cd/dvd  TSSTcorp DVD-ROM TS-L333H ID03  /dev/sr0 [2:0:0:0]    cd/dvd  IMM      Virtual CD/DVD   0316  /dev/sr1 [3:0:0:0]    disk    IBM-ESXS MBF2300RC        SB27  -       [3:0:1:0]    disk    IBM-ESXS MBF2300RC        SB27  -       [3:1:1:0]    disk    LSILOGIC Logical Volume   3000  /dev/sda [4:0:0:0]    disk    IBM      2145             0000  /dev/sdb [4:0:0:1]    disk    IBM      2145             0000  /dev/sdc [4:0:2:0]    disk    IBM      2145             0000  /dev/sdd [4:0:2:1]    disk    IBM      2145             0000  /dev/sde [5:0:2:0]    disk    IBM      2145             0000  /dev/sdf [5:0:2:1]    disk    IBM      2145             0000  /dev/sdg [5:0:4:0]    disk    IBM      2145             0000  /dev/sdh [5:0:4:1]    disk    IBM      2145             0000  /dev/sdi [backcolor=rgb(245, 245, 245) !important][url=][/url]

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1. multipath常用操作：

multipath -r （修改multipath.conf配置文件之后重新加载）
  \5 ~7 t+ j: `$ Y1 \/ nmultipath -ll （查看多路径状态）
8 E' Z# M) B" omultipath -v2 （格式化路径，检测路径，合并路径）
multipath -v3 （查看多路径详情blacklist、whitelist和设备wwid）
- \, O, ]* }1 @3 C0 Z  {multipath -F （删除现有链路）

2. multipath文件详细介绍

接下来的工作就是要编辑/etc/multipath.conf的配置文件

multipath.conf主要包括blacklist、multipaths、devices三部份的配置
blacklist配置
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blacklist {

　　devnode "^sda"

}

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multipaths {
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- |7 @: H1 P3 m) o. z$ R: r( B) l　　　　wwid **************** 　　　　　　#此值multipath -v3可以看到
( |, w) H, }7 m! J- Z　　　　alias iscsi-dm0 　　　　　　　　#映射后的别名,可以随便取
  y9 k8 p( u7 H　　　　path_grouping_policy multibus 　　#路径组策略
　　　　path_checker tur 　　　　　　　　#决定路径状态的方法
$ X6 U1 E7 c' C2 q　　　　path_selector "round-robin 0" 　　#选择那条路径进行下一个IO操作的方法
　　}
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devices {
　　device {
　　　　vendor "iSCSI-Enterprise" 　　　　　　　　　　#厂商名称
8 g1 L; G  K# Q6 P. u5 w　　　　product "Virtual disk" 　　　　　　　　　　　　#产品型号
　　　　path_grouping_policy multibus 　　　　　　　　#默认的路径组策略
　　　　getuid_callout "/sbin/scsi_id -g -u -s /block/%n"　#获得唯一设备号使用的默认程序
: {9 R6 f0 t% T　　　　prio_callout      "/sbin/acs_prio_alua %d" 　　　  #获取有限级数值使用的默认程序
　　　　path_checker readsector0 　　　　　　　　　　#决定路径状态的方法
　　　　path_selector "round-robin 0" 　　#选择那条路径进行下一个IO操作的方法
　　　　failback        immediate 　　　　#故障恢复的模式
/ Q4 Y# A7 t+ P( g, t) l3 r   　　　no_path_retry      queue 　　　　#在disable queue之前系统尝试使用失效路径的次数的数值
" N/ ^, V, \& D, L  　　　　rr_min_io       100 　　　　　　#在当前的用户组中，在切换到另外一条路径之前的IO请求的数目
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相关参数的标准文档的介绍：

Attribute

Description

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wwid

Specifies the WWID of the multipath device to which the multipath attributes apply. This parameter is mandatory for this section of themultipath.conf file.

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alias

Specifies the symbolic name for the multipath device to which themultipath attributes apply. If you are using user_friendly_names, do not set this value tompathn; this may conflict with an automatically assigned user friendly name and give you incorrect device node names.

path_grouping_policy

Specifies the default path grouping policy to apply to unspecified multipaths. Possible values include:

failover = 1 path per priority group

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multibus = all valid paths in 1 priority group

group_by_serial = 1 priority group per detected serial number

group_by_prio = 1 priority group per path priority value

group_by_node_name = 1 priority group per target node name

path_selector

Specifies the default algorithm to use in determining what path to use for the next I/O operation. Possible values include:

round-robin 0: Loop through every path in the path group, sending the same amount of I/O to each.

queue-length 0: Send the next bunch of I/O down the path with the least number of outstanding I/O requests.

service-time 0: Send the next bunch of I/O down the path with the shortest estimated service time, which is determined by dividing the total size of the outstanding I/O to each path by its relative throughput.

failback

Manages path group failback.

A value of immediate specifies immediate failback to the highest priority path group that contains active paths.

A value of manual specifies that there should not be immediate failback but that failback can happen only with operator intervention.

A value of followover specifies that automatic failback should be performed when the first path of a path group becomes active. This keeps a node from automatically failing back when another node requested the failover.

A numeric value greater than zero specifies deferred failback, expressed in seconds.

prio

Specifies the default function to call to obtain a path priority value. For example, the ALUA bits in SPC-3 provide an exploitableprio value. Possible values include:

const: Set a priority of 1 to all paths.

emc: Generate the path priority for EMC arrays.

alua: Generate the path priority based on the SCSI-3 ALUA settings.

tpg_pref: Generate the path priority based on the SCSI-3 ALUA settings, using the preferred port bit.

ontap: Generate the path priority for NetApp arrays.

rdac: Generate the path priority for LSI/Engenio RDAC controller.

hp_sw: Generate the path priority for Compaq/HP controller in active/standby mode.

hds: Generate the path priority for Hitachi HDS Modular storage arrays.

no_path_retry

A numeric value for this attribute specifies the number of times the system should attempt to use a failed path before disabling queueing.

A value of fail indicates immediate failure, without queueing.

A value of queue indicates that queueing should not stop until the path is fixed.

rr_min_io

Specifies the number of I/O requests to route to a path before switching to the next path in the current path group. This setting is only for systems running kernels older that 2.6.31. Newer systems should userr_min_io_rq. The default value is 1000.

rr_min_io_rq

Specifies the number of I/O requests to route to a path before switching to the next path in the current path group, using request-based device-mapper-multipath. This setting should be used on systems running current kernels. On systems running kernels older than 2.6.31, use rr_min_io. The default value is 1.

rr_weight

If set to priorities, then instead of sending rr_min_io requests to a path before callingpath_selector to choose the next path, the number of requests to send is determined byrr_min_io times the path's priority, as determined by the prio function. If set touniform, all path weights are equal.

flush_on_last_del

If set to yes, then multipath will disable queueing when the last path to a device has been deleted.

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multipath与oracle ASM结合

https://www.cnblogs.com/jyzhao/p/7208620.html

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已有配置文件：

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defaults {    polling_interval    30    failback            immediate    no_path_retry       5    rr_min_io           100    path_checker        tur    user_friendly_names yes }devnode_blacklist {        devnode "sda"}devices {    device {        vendor                   "IBM"        product                  "2145"        path_grouping_policy     group_by_prio        prio_callout             "/sbin/mpath_prio_alua /dev/%n"    }    device {        vendor                   "IBM"        product                  "1750500"        path_grouping_policy     group_by_prio        prio_callout             "/sbin/mpath_prio_alua /dev/%n"    }    device {        vendor                   "IBM"        product                  "2107900"        path_grouping_policy     group_by_serial    }    device {        vendor                   "IBM"        product                  "2105800"        path_grouping_policy     group_by_serial    }}multipaths {        multipath {                wwid    36005076801820709e000000000000043                alias   dm-vote01        }}[backcolor=rgb(245, 245, 245) !important][url=][/url]