The article explains how long a datanode has to be offline before the data blocks are re-replicated to other data nodes within the cluster. This can be useful to know if there is a need to avoid replication because of cluster load, capacity or locality (for example in the case of Pivotal HDB 1.x).
By default, the datanode has to be unavailable (not sending a heartbeat to the namenode) for 10.5 minutes before the blocks on the unavailable datanode are replicated. The time to mark a datanode as dead is:
(dfs.namenode.heartbeat.recheck-interval * 2) + (10 * 1000 * heartbeatInterval)
If the default values are applied to the above formula:
(300000 * 2) + (10 * 1000 * 3) = 630000 Milliseconds = 10.5 Minutes.
If there is a need to take up the time before replication starts this can be done by changing dfs.namenode.heartbeat.recheck-interval to a higher value by adding the configuration and value into AMBARI / HDFS / Configurations / Custom hdfs-site