04-docker 数据存储

1.默认安装使用的是loop-lvm的模式做后端存储，这个肯对对后面的实验会造成影响，而且docker官方也不建议在生产环境下使用loop-lvm

[root@docker03 ~]# ls -lsh /var/lib/docker/devicemapper/devicemapper/
total 19M
 18M -rw------- 1 root root 100G Mar 20 11:25 data
612K -rw------- 1 root root 2.0G Mar 20 11:56 metadata

data     [存放数据]
metadata [存放元数据]

的大小从输出可以看出初始化默认为 100G 和 2G 大小，都是稀疏文件，使用多少占用多少。
Docker 在初始化的过程中，创建 data 和 metadata 这两个稀疏文件，并分别附加到回环设备/dev/loop0 和 /dev/loop1 上，然后基于回环设备创建 thin pool。 默认一个 container 最大存放数据不超过 10G[注：docker 1.8 之后默认的大小已经为 100G，建议生产环境针对 container pool 大小监控。]，如果需要调整则需要修改 /etc/sysconfig/docker 配置文件添加相关选项 --storage-opt 调整即可（详细参考 man docker 查看 STORAGE DRIVER OPTIONS 具体参数说明）。

2.查看docker 存储信息

[root@docker03 ~]# docker info
Containers: 1
 Running: 0
 Paused: 0
 Stopped: 1
Images: 1
Server Version: 17.12.1-ce
Storage Driver: devicemapper
 Pool Name: docker-8:3-532308-pool
 Pool Blocksize: 65.54kB
 Base Device Size: 10.74GB
 Backing Filesystem: xfs
 Udev Sync Supported: true
 Data file: /dev/loop0
 Metadata file: /dev/loop1
 Data loop file: /var/lib/docker/devicemapper/devicemapper/data
 Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
 Data Space Used: 19.4MB
 Data Space Total: 107.4GB
 Data Space Available: 35.92GB
 Metadata Space Used: 593.9kB
 Metadata Space Total: 2.147GB
 Metadata Space Available: 2.147GB
 Thin Pool Minimum Free Space: 10.74GB
 Deferred Removal Enabled: true
 Deferred Deletion Enabled: true
 Deferred Deleted Device Count: 0
 Library Version: 1.02.140-RHEL7 (2017-05-03)
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 9b55aab90508bd389d7654c4baf173a981477d55
runc version: 9f9c96235cc97674e935002fc3d78361b696a69e
init version: 949e6fa
Security Options:
 seccomp
  Profile: default
Kernel Version: 3.10.0-327.el7.x86_64
Operating System: CentOS Linux 7 (Core)
OSType: linux
Architecture: x86_64
CPUs: 1
Total Memory: 1.782GiB
Name: docker03
ID: UJBD:FJSQ:CIVU:YXWM:2BQX:DRAM:66RA:LKW7:E64F:YMRM:WSYZ:EUGQ
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Registry Mirrors:
 https://de378wx8.mirror.aliyuncs.com/
Live Restore Enabled: false

WARNING: devicemapper: usage of loopback devices is strongly discouraged for production use.
         Use `--storage-opt dm.thinpooldev` to specify a custom block storage device.

 

参考资料：http://blog.51cto.com/dengaosky/2062021