Enabling additional service instances

To ensure a base level of resiliency, MicroCeph will always try to enable a sufficient number of instances for certain services in the cluster. This number is set to three by default.

The services affected by this include:

• MON (Monitor service)

• MDS (Metadata service)

• MGR (Manager service)

Cluster designs that call for extra service instances, however, can be satisfied by manual means. In addition to the above-listed services, the following service can be added manually to a node:

• RGW (RADOS Gateway service)

This is the purpose of the enable command. It manually enables a new instance of a service on a node.

The syntax is:

sudo microceph enable <service> --target <destination> ...

Where the service value is one of ‘mon’, ‘mds’, ‘mgr’, and ‘rgw’. The destination is a node name as discerned by the output of the status command:

sudo microceph status

For a given service, the enable command may support extra parameters. These can be discovered by querying for help for the respective service:

sudo microceph enable <service> --help

Example: enable an RGW service

First check the status of the cluster to get node names and an overview of existing services:

sudo microceph status

MicroCeph deployment summary:
- node1-2c3eb41e-14e8-465d-9877-df36f5d80922 (10.111.153.78)
  Services: mds, mgr, mon, osd
  Disks: 3
- workbook (192.168.29.152)
  Services: mds, mgr, mon
  Disks: 0

View any possible extra parameters for the RGW service:

sudo microceph enable rgw --help

To enable the RGW service on node1 and specify a value for extra parameter port:

sudo microceph enable rgw --target node1 --port 8080

Finally, view cluster status again and verify expected changes:

sudo microceph status

MicroCeph deployment summary:
- node1 (10.111.153.78)
  Services: mds, mgr, mon, rgw, osd
  Disks: 3
- workbook (192.168.29.152)
  Services: mds, mgr, mon
  Disks: 0