:: localhost docker-storage-setup: Volume group "centos" has insufficient free space ( extents): required.
Apr :: localhost systemd: docker-storage-setup.service: main process exited, code=exited, status=/NOTINSTALLED
Apr :: localhost systemd: Failed to start Docker Storage Setup.
Apr :: localhost systemd: Unit docker-storage-setup.service entered failed state.
Apr :: localhost systemd: docker-storage-setup.service failed.
Apr :: localhost systemd: Starting Docker Application Container Engine...
Apr :: localhost journal: Forwarding stdin to journald using Priority Informational and tag docker
Apr :: localhost kernel: loop: module loaded
Apr :: localhost journal: time="2016-04-27T15:15:38.376521502+08:00" level=warning msg="Usage of loopback devices is strongly discouraged for production use. Please use `--storage-opt dm.thinpooldev` or use `man docker` to refer to dm.thinpooldev section."
Apr :: localhost systemd: Device dev-disk-by\x2duuid-81caf5ff\x2dd883\x2d45a2\x2db20c\x2d31a41d07ad2c.device appeared twice with different sysfs paths /sys/devices/virtual/block/loop0 and /sys/devices/virtual/block/dm-
Apr :: localhost journal: time="2016-04-27T15:15:38.571170482+08:00" level=info msg="[graphdriver] using prior storage driver \"devicemapper\""
Apr :: localhost journal: time="2016-04-27T15:15:38.572029145+08:00" level=warning msg="Docker could not enable SELinux on the host system"
Apr :: localhost kernel: Bridge firewalling registered
Apr :: localhost journal: time="2016-04-27T15:15:46.069579911+08:00" level=warning msg="Running modprobe bridge br_netfilter failed with message: modprobe: WARNING: Module br_netfilter not found.\ninsmod /lib/modules/3.10.0-229.4.2.el7.x86_64/kernel/net/llc/llc.ko \ninsmod /lib/modules/3.10.0-229.4.2.el7.x86_64/kernel/net/802/stp.ko \ninsmod /lib/modules/3.10.0-229.4.2.el7.x86_64/kernel/net/bridge/bridge.ko \n, error: exit status 1"
Apr :: localhost kernel: nf_conntrack version 0.5. ( buckets, max)
Apr :: localhost journal: time="2016-04-27T15:15:46.118260335+08:00" level=info msg="Firewalld running: false"
Apr :: localhost journal: time="2016-04-27T15:15:46.366809062+08:00" level=fatal msg="Error starting daemon: Error initializing network controller: could not delete the default bridge network: network bridge has active endpoints"
Apr :: localhost systemd: Started Docker Application Container Engine.
Apr :: localhost systemd: Started Session of user root.
Apr :: localhost systemd: Starting Session of user root.
Apr :: localhost systemd: Started Session of user root.
Apr :: localhost systemd: Starting Session of user root.
Apr :: localhost systemd: Started Session of user root.
Apr :: localhost systemd: Starting Session of user root.
Apr :: localhost systemd: Started Session of user root.
Apr :: localhost systemd: Starting Session of user root.
Apr :: localhost systemd: Started Session of user root.
Apr :: localhost systemd: Starting Session of user root.
Apr :: localhost systemd: Starting Docker Storage Setup...
Apr :: localhost docker-storage-setup: Rounding up size to full physical extent 264.00 MiB
Apr :: localhost docker-storage-setup: Volume group "centos" has insufficient free space ( extents): required.
Apr :: localhost systemd: docker-storage-setup.service: main process exited, code=exited, status=/NOTINSTALLED
Apr :: localhost systemd: Failed to start Docker Storage Setup.
Apr :: localhost systemd: Unit docker-storage-setup.service entered failed state.
Apr :: localhost systemd: docker-storage-setup.service failed.
OPTIONS='--selinux-enabled=false --graph=/home/lib/docker' 解决，但是没有以前的镜像文件了
------------------------------------------------------------------------------
cd /var/lib
sudo cp -rf docker docker.bak
sudo cp -rf docker /<my_new_location>/
sudo ln -s /<my_new_location>/docker docker
sudo /etc/init.d/docker start
5、docker无法启动，原因有可能磁盘不够，或者没有解析到。
Nov 19 20:29:36 centos7 systemd: Starting Docker Storage Setup...
Nov 19 20:29:36 centos7 docker-storage-setup: Rounding up size to full physical extent 32.00 MiB
Nov 19 20:29:36 centos7 docker-storage-setup: Volume group "centos_centos7" has insufficient free space (0 extents): 8 required.
Nov 19 20:29:36 centos7 systemd: docker-storage-setup.service: main process exited, code=exited, status=5/NOTINSSTALLED
Nov 19 20:29:36 centos7 systemd: Failed to start Docker Storage Setup.
Nov 19 20:29:36 centos7 systemd: Unit docker-storage-setup.service entered failed state.
Nov 19 20:29:36 centos7 systemd: Starting Docker Application Container Engine...
Nov 19 20:29:36 centos7 docker: time="2015-11-19T20:29:36.538243264+08:00" level=info msg="Listening for HTTP on unix (/var/run/docker.sock)"
Nov 19 20:29:36 centos7 docker: time="2015-11-19T20:29:36.540394247+08:00" level=error msg="WARNING: No --storage-opt dm.thinpooldev specified, using loopback; this configuration is strongly discouraged for production use"
解决办法：
增加vg容量，重启机器试试
不行就删除 /usr/lib/systemd/system/docker.service 里的DOCKER_STORAGE_OPTIONS
systemctl daemon-reload
systemctl restart docker.service
6、还是无法启动docker，原因可能为docker没有识别到正常的thinpooldev，需要手动指定
Error starting daemon: error initializing graphdriver: EOF
/usr/bin/docker daemon --selinux-enabled --storage-driver devicemapper --storage-opt dm.fs=xfs --storage-opt dm.thinpooldev=/dev/mapper/centos_centos7-docker--pool-tpool
解决办法：
https://gist.github.com/joshix/ec1673f2791bf5cb352f#file-thin-pool-md
dmsetup status
找到tpool结尾的那行，比如centos_centos7-docker--pool-tpool
修改文件
vim /etc/sysconfig/docker-storage
DOCKER_STORAGE_OPTIONS=--storage-driver devicemapper --storage-opt dm.fs=xfs --storage-opt dm.thinpooldev=/dev/mapper/centos_centos7-docker--pool-tpool
重启
systemctl daemon-reload
systemctl restart docker.service