Obtaining the Status of Domain Resources

To obtain the status of domain resources, invoke the NuoDB Manager show domain summary command. This command lists the brokers, databases and processes that are recorded in the durable domain configuration. According to the kind of resource, the command output indicates if the resource is connected, running, active or unreachable. For example, consider a domain with two brokers and one database. Invoking show domain summary would display something like this:

nuodb [mydomain] > show domain summary

Hosts:
[broker] * [broker] ip-172-31-13-183/172.31.13.183:48004 (us-west) CONNECTED
[broker]  mylinux.mycompany.com/127.0.0.1:48114 (us-west) CONNECTED

Database: myDatabase, (unmanaged), processes [2 TE, 2 SM], ACTIVE
[SM] mylinux.mycompany.com/10.1.37.68:64977 (us-west) [pid = 45034] [nodeId = 1] RUNNING
[TE] mylinux.mycompany.com/10.1.37.68:64979 (us-west) [pid = 45035] [nodeId = 2] RUNNING
[SM] mylinux.mycompany.com/127.0.0.1:64982 (us-west) [pid = 45036] [nodeId = 3] RUNNING
[TE] mylinux.mycompany.com/127.0.0.1:64986 (us-west) [pid = 45037] [nodeId = 4] RUNNING
nuodb [mydomain] > 

Now suppose that the host that the second listed broker is running on terminates, perhaps due to a power outage. The second listed broker remains recorded in the durable domain configuration. But the first listed broker is not receiving any acknowledgements that the second broker is running (see Setting Up Failure Detection). Now if you invoke show domain summary, the result shows that the second listed broker is unreachable and the database processes that are running on the same host are also unreachable:

nuodb [mydomain] > show domain summary

Hosts:
[broker] * ip-172-31-13-183/172.31.13.183:48004 (us-west) CONNECTED
[broker] mylinux.mycompany.com/127.0.0.1:48114 (us-west) UNREACHABLE

Database: myDatabase, template [Minimally Redundant] UNMET, processes [2 TE, 2 SM], ACTIVE
[SM] mylinux.mycompany.com/10.1.37.68:64977 (us-west) [pid = 45034] [nodeId = 1] RUNNING
[TE] mylinux.mycompany.com/10.1.37.68:64979 (us-west) [pid = 45035] [nodeId = 2] RUNNING
[SM] mylinux.mycompany.com/127.0.0.1:64982 (us-west) [pid = 45036] [nodeId = 3] UNREACHABLE
[TE] mylinux.mycompany.com/127.0.0.1:64986 (us-west) [pid = 45037] [nodeId = 4] UNREACHABLE
nuodb [mydomain] > 

An unreachable broker can often restart itself and become connected again. If an unreachable broker is unable to restart itself then it is permanently lost and you need to deprovision it. To deprovision the lost broker, the domain must have a broker quorumIn a domain, a quorum is the minimum number of brokers that must acknowledge a change to the durable domain configuration for that change to be made. Usually, this is a simple majority. Many operations in the management tier require acknowledgement from a majority of brokers in the domain in order to ensure safety (never returning an incorrect result) in case of failure.. See About Broker Quorum.

For additional information and examples, see show domain summary.