Log Aggregation and Storage
Fluentd
uses a round-robin approach when writing logs to Elasticsearch
nodes. If an Elasticsearch node in unavailable, Fluentd
can fail over log
storage to another Elasticsearch node.
Each Fluentd
service connects to each Elasticsearch node that you configure
to aggregate and store logs. The Elasticsearch nodes are set when you configure Monitoring with the Installer or
when you run configure.sh with the
-ES
parameter.
The Elasticsearch index directory is shared among all the Elasticsearch nodes in the cluster.
When you use the Installer to install Elasticsearch, each
Elasticsearch node writes index data to /opt/mapr/es_db
, unless you specified
a different location during the installation. When you manually install Elasticsearch, each
Elasticsearch node writes index data to
/opt/mapr/elasticsearch/elasticsearch-<version>/var/lib/MaprMonitoring/
,
unless you specified a different location using the configure.sh
-ESDB
option. For a cluster with one Elasticsearch node, the index directory
is allocated 5 shards. For clusters with 2 or more Elasticsearch nodes, the index directory is
allocated a number of shards equal to 3 times the number of Elasticsearch nodes in the
cluster.
Fluentd
does not require additional configuration to enable automatic
failover to an available Elasticsearch node. However, it is important that at least three
Elasticsearch nodes are configured to aggregate and store logs so that failure of one node
does not prevent logs from being used for monitoring purposes. Based on your environment, more
Elasticsearch nodes may be required. Service Layout Guidelines for Large Clusters.
For more information about Elasticsearch, see the Elastic website.