1. Centos 系統Docker預設檔案儲存使用devicemapper (loop), 官方建議生產環境下將預設的devicemapper (loop) 方式改為devicemapper (direct-lvm).

2. 本文直接將預設的devicemapper 改為 overlay

3. 需要刪除Docker預設的/var/lib/docker 資料 (原有資料回丟失!)

檢視Docker 資訊

[[email protected]~]# docker info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 1
 

Server Version: 1.12.5
Storage Driver: devicemapper
...

停止Docker服務

[[email protected]~]# service docker stop

刪除Docker資料

[[email protected]~]# rm -rf /var/lib/docker

增加overlay module

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

重啟主機

[[email protected]
 
~]# shutdown -r now

確認overlay生效

[[email protected]~]# lsmod |grep over
overlay       42451  1

修改Docker啟動方式,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
 

啟動Docker daemon

[[email protected]~]# service docker start
Redirecting to /bin/systemctl start  docker.service

[[email protected]~]# docker info |grep overlay
Storage Driver: overlay
...

修改後Docker啟動失敗, 重灌Docker

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

[[email protected]~]# 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 實驗版本

[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

[[email protected]~]# yum -y install docker-engine