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When loss of a NuoDB Admin process causes loss of admin process 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. and you cannot restart that admin process then you must re-establish admin process quorum. The following procedure re-establishes admin process quorum by ensuring that the lost admin process is not counted when determining whether a majority of admin processes in the durable domain configuration is available. To re-establish admin process quorum:
To make it easy to obtain the stable ID of the lost admin process host, invoke the NuoDB Manager
set property command to show the stable ID in domain status output. For example:
set property showHostStableId value true
show domain summarycommand.
On each host that was running a surviving admin process, with the admin process shut down, in the
NUODB_HOME/bin directory, invoke the
agent-tool utility to ban the unavailable admin process. This prevents the admin process of the unavailable admin process from continuing to be a resource in the domain. For example, if the stable ID of the unavailable admin process host is
123456789 then you would enter a command such as the following:
agent-tool membership --ban uuid:123456789
--reset-broker-stateoption. This removes the old stable ID and the old Raft data. When the admin process starts, it gets the durable domain configurationThe durable domain configuration provides domain configuration information that is stored consistently on each NuoDB Admin process in the domain by means of a Raft log. from another admin process.
With admin process quorum established, any banned admin processes are removed from the durable domain configuration. The banned admin processes cannot use the same stable ID to re-peer into the domain.