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Starting and Stopping Ozone Services

Ozone services (Ozone Manager, Storage Container Manager, Datanode, Recon, S3 Gateway) are typically managed using the ozone command-line interface (CLI) tool provided with the Ozone distribution.

Using the ozone --daemon Command​

The primary way to start and stop individual Ozone daemons on their respective hosts is using the ozone --daemon command.

Syntax:

ozone --daemon <start|stop> <service>

Where <service> is one of:

  • om (Ozone Manager)
  • scm (Storage Container Manager)
  • datanode
  • recon
  • s3g (S3 Gateway)

Note: You must run these commands on the host where the specific service is configured to run.

Start Order​

It's generally recommended to start services in the following order:

  1. Storage Container Manager (SCM): The SCM must be running before Ozone Managers and Datanodes can function correctly.
  2. Ozone Manager (OM): The OM depends on the SCM.
  3. Datanodes: Datanodes register with both SCM and OM.
  4. S3 Gateway (S3G): Depends on OM.
  5. Recon: Depends on OM and SCM.

Stop Order​

Stop services in the reverse order of startup to minimize disruption:

  1. Recon
  2. S3 Gateway (S3G)
  3. Datanodes
  4. Ozone Manager (OM)
  5. Storage Container Manager (SCM)

Commands by Service​

Storage Container Manager (SCM)​

Run these commands on the SCM host(s).

  • Start: 
    ozone --daemon start scm
  • Stop: 
    ozone --daemon stop scm

Ozone Manager (OM)​

Run these commands on the OM host(s).

  • Start: 
    ozone --daemon start om
  • Stop: 
    ozone --daemon stop om

Datanode​

Run these commands on all Datanode hosts.

  • Start: 
    ozone --daemon start datanode
  • Stop: 
    ozone --daemon stop datanode

Recon​

Run these commands on the Recon host.

  • Start: 
    ozone --daemon start recon
  • Stop: 
    ozone --daemon stop recon

S3 Gateway (S3G)​

Run these commands on the S3 Gateway host(s).

  • Start: 
    ozone --daemon start s3g
  • Stop: 
    ozone --daemon stop s3g

Checking Service Status​

While the ozone --daemon command doesn't have a status option, you can check if the service processes are running using standard Linux/Unix tools like ps or jps.

Example using jps:

jps -lm | grep -i ozone
# Look for processes like:
# ... OzoneManager
# ... StorageContainerManager
# ... HddsDatanodeService
# ... ReconServer
# ... OzoneS3Gateway

Alternatively, check the service logs (usually in the configured Ozone log directory) or the respective Web UIs for status information.