Multipath 安装和 Openstack Nova + Cinder 配置

Multipath 安装

不知道，不了解 multipath 的可以看下这个文档（看到 Overview 就差不多了），介绍的很不错：

https://www.sourceware.org/lvm2/wiki/MultipathUsageGuide

1. 安装 device-mapper-multipath RPM 包

检查安装包是否存在（不同 Linux 环境显示的结果不一样）：

[root@controller ~]# rpm -qa | grep device-mapper-multipath
device-mapper-multipath-libs-0.4.9-77.el7.x86_64
device-mapper-multipath-0.4.9-77.el7.x86_64
 
 
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如果不存在，安装该 RPM 包：

[root@controller ~]# yum install device-mapper-multipath
 
 
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2. 手动生成 /etc/multipath.conf 文件，命令如下：

[root@controller ~]# mpathconf --enable
 
 
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3. 编辑 multipath.conf 文件（非必选）

根据自己的配置需求编辑这个配置文件，最简单的是不改文件。

vim /etc/multipath.conf
defaults {
        user_friendly_names yes
        path_grouping_policy multibus
        find_multipaths yes
        no_path_retry fail
        failback immediate
}
 
 
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4. 重启 multipath 服务

请务必确认服务的状态！

[root@controller ~]# systemctl restart multipathd.service
[root@controller ~]# systemctl status multipathd.service
 
 
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如果服务为 failed，请先排查错误，确认状态正常之后再做后面的配置：
Ps： 很多小伙伴都没有这个习惯，导致很多事情做完之后才发现前面的有问题，然后导致连锁问题。

[root@controller ~]# systemctl status multipathd.service
multipathd.service - Device-Mapper Multipath Device Controller
   Loaded: loaded (/usr/lib/systemd/system/multipathd.service; enabled)
   Active: active (running) since Fri 2016-12-30 13:35:18 CST; 1 weeks 2 days ago
  Process: 551 ExecStart=/sbin/multipathd (code=exited, status=0/SUCCESS)
  Process: 534 ExecStartPre=/sbin/multipath -A (code=exited, status=0/SUCCESS)
  Process: 498 ExecStartPre=/sbin/modprobe dm-multipath (code=exited, status=0/SUCCESS)
 Main PID: 558 (multipathd)
   CGroup: /system.slice/multipathd.service
           └─558 /sbin/multipathd

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.

 
 
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Openstack Nova + Cinder 配置

1. 修改 nova 以及 cinder 配置文件

(1) 修改 nova.conf

Use multipath connection of the iSCSI or FC volume (boolean value)
编辑 nova.conf，libvirt 下配置 iscsi_use_multipath=true

[root@controller ~]# grep multipath  /etc/nova/nova.conf
# Use multipath connection of the iSCSI volume (boolean value)
#iscsi_use_multipath=false
iscsi_use_multipath=true
# Use multipath connection of the iSER volume (boolean value)
#iser_use_multipath=false
 
 
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(2) 修改 cinder.conf

Do we attach/detach volumes in cinder using multipath for volume to image and image to volume transfers? (boolean value)
编辑 cinder.conf，在使用的 backend 中配置 use_multipath_for_image_xfer=true

# Do we attach/detach volumes in cinder using multipath for volume to image and
# image to volume transfers? (boolean value)
#use_multipath_for_image_xfer = false

# If this is set to True, attachment of volumes for image transfer will be
# aborted when multipathd is not running. Otherwise, it will fallback to single
# path. (boolean value)
#enforce_multipath_for_image_xfer = false
 
 
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2. 重启 nova 和 cinder 相关服务

(1) 重启 nova-compute 服务（attach multipath）

systemctl restart openstack-nova-compute.service

(2) 重启 cinder-volume 服务（cinder multipath）

systemctl restart openstack-cinder-volume.service