Data Subsystem

How To Start DataNode

Start a DataNode process by execute the server binary of CubeFS you built with -c argument and specify configuration file. Usually, the number of datanode instances needs to be more than three, but in a production environment, in order to consider disaster recovery backup, at least four datanode instances are required.

nohup cfs-server -c datanode.json &

Configurations

Properties
Key	Type	Description	Mandatory
role	string	Role of process and must be set to datanode	Yes
listen	string	Port of TCP network to be listen	Yes
localIP	string	IP of network to be choose	No,If not specified, the ip address used to communicate with the master is used.
prof	string	Port of HTTP based prof and api service	Yes
logDir	string	Path for log file storage	Yes
logLevel	string	Level operation for logging. Default is error	No
raftHeartbeat	string	Port of raft heartbeat TCP network to be listen	Yes
raftReplica	string	Port of raft replicate TCP network to be listen	Yes
raftDir	string	Path for raft log file storage	No
consulAddr	string	Addresses of monitor system	No
exporterPort	string	Port for monitor system	No
masterAddr	string slice	Addresses of master server	Yes
zoneName	string	Specified zone. `default` by default.	No
disks	string slice	Format: PATH:RETAIN. PATH: Disk mount point. RETAIN: Retain space. (Ranges: 20G-50G.)	Yes

Example:

{
    "role": "datanode",
    "listen": "17310",
    "prof": "17320",
    "logDir": "/cfs/datanode/log",
    "logLevel": "info",
    "raftHeartbeat": "17330",
    "raftReplica": "17340",
    "raftDir": "/cfs/datanode/log",
    "consulAddr": "http://consul.prometheus-cfs.local",
    "exporterPort": 9502,
    "masterAddr": [
         "10.196.59.198:17010",
         "10.196.59.199:17010",
         "10.196.59.200:17010"
    ],
     "disks": [
        "/data0:10737418240",
        "/data1:10737418240"
    ]
}

Notice

Since datanode uses SEEK_HOLE and SEEK_DATA operations which is supported by XFS (since Linux 3.5) and ext4 (since Linux 3.8), users should pay attention to the Linux kernel version on which datanodes are deployed.

listen, raftHeartbeat, raftReplica can’t be modified after boot startup first time.

Above config would be stored under directory raftDir in constcfg file. If need modified forcely, you must delete this file manually.

These configuration items associated with master’s datanode infomation. If they have been modified, master would’t be found old datanode.