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Website: very minor tweaks to docs/internals/anti-entropy.html.

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Ryan Breen 2015-03-29 10:53:49 -04:00
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website/source/docs/internals/anti-entropy.html.markdown
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@ -57,17 +57,20 @@ consolidated and consistent view of the cluster.
<a name="anti-entropy"></a>
### Anti-Entropy
Consul has a clear separation between the global service catalog and the agent
local state as discussed above. Reconciling these two is done using an
anti-entropy mechanism.
Entropy is the tendency of systems to become increasingly disordered. Consul's
anti-entropy mechanisms are designed to counter this tendency, to keep the
state of the cluster ordered even through failures of its components.
Anti-entropy is a syncronization of the local agent state and the catalog. For
example, when a user registers a new service or check with the agent, the agent
in turn notifies the catalog that this new check exists. Similarly, when a check
is deleted from the agent, it is consequently removed from the catalog as well.
Consul has a clear separation between the global service catalog and the agent
local state as discussed above. The anti-entropy mechanism reconciles these two
views of the world: anti-entropy is a syncronization of the local agent state and
the catalog. For example, when a user registers a new service or check with the
agent, the agent in turn notifies the catalog that this new check exists.
Similarly, when a check is deleted from the agent, it is consequently removed from
the catalog as well.
Anti-entropy is also used to update availability information. As agents run
their health checks, their status may change, in which case their new status
their health checks, their status may change in which case their new status
is synced to the catalog. Using this information, the catalog can respond
intelligently to queries about its nodes and services based on their
availability.
@ -76,7 +79,7 @@ During this synchronization, the catalog is also checked for correctness. If
any services or checks exist in the catalog that the agent is not aware of, they
will be automatically removed to make the catalog reflect the proper set of
services and health information for that agent. Consul treats the state of the
agent as authoritative, meaning if there are any differences between the agent
agent as authoritative; if there are any differences between the agent
and catalog view, the agent local view will always be used.
### Periodic Synchronization
@ -87,9 +90,9 @@ status to the catalog. This ensures that the catalog closely matches the agent's
true state. This also allows Consul to re-populate the service catalog even in
the case of complete data loss.
The amount of time between periodic anti-entropy runs will vary based on cluster
size to avoid saturation. The table below describes the periodic sync times and
how they change as the Consul cluster grows.
To avoid saturation, the amount of time between periodic anti-entropy runs will
vary based on cluster size. The table below defines the relationship between
cluster size and sync interval:
<table class="table table-bordered table-striped">
<tr>