更改Centos7 Docker 1.12文件系统为overlay

Centos 系统Docker默认文件存储使用devicemapper (loop), 官方建议生产环境下将默认的devicemapper (loop) 方式改为devicemapper (direct-lvm).

本文直接将默认的devicemapper 改为 overlay

需要删除Docker默认的/var/lib/docker 数据 (原有数据回丢失!)

查看Docker 信息

[root@~]# docker info
Containers: 0
Running: 0
Paused: 0
Stopped: 0
Images: 1
Server Version: 1.12.5
Storage Driver: devicemapper
...

停止Docker服务

[root@~]# service docker stop

删除Docker数据

[root@~]# rm -rf /var/lib/docker

增加overlay module

[root@~]# echo "overlay" > /etc/modules-load.d/overlay.conf

重启主机

[root@~]# shutdown -r now

确认overlay生效

[root@~]# lsmod |grep over
overlay       42451  1

修改Docker启动方式,指定storage-driver

[root@~]# mkdir -p /etc/systemd/system/docker.service.d
[root@~]# cat >/etc/systemd/system/docker.service.d/override.conf<<EOF
[Service]
ExecStart=
ExecStart=/usr/bin/docker daemon --storage-driver=overlay
EOF

启动Docker daemon

[root@~]# service docker start
Redirecting to /bin/systemctl start  docker.service

[root@~]# docker info |grep overlay
Storage Driver: overlay
...

修改后Docker启动失败, 重装Docker

[root@~]#rpm -qa |grep docker
docker-engine-selinux-1.12.6-1.el7.centos.noarch
docker-engine-1.12.6-1.el7.centos.x86_64

[root@~]# yum -y remove docker-engine-selinux-1.12.6-1.el7.centos.noarch docker-engine-1.12.6-1.el7.centos.x86_64

下面使用的是1.12 实验版本

[root@~]# cat > /etc/yum.repos.d/docker.repo <<-EOF
[dockerrepo]
name=Docker Repository
baseurl=https://yum.dockerproject.org/repo/experimental/centos/7/
enabled=1
gpgcheck=1
gpgkey=https://yum.dockerproject.org/gpg
EOF

[root@~]# yum -y install docker-engine