Yes, it is mostly geared towards replication greater than 1. One of the reasons for waiting for this threshold is to avoid HDFS starting unnecessary replications of blocks at the start up when some of the datanodes are slower to start up.
When the replication is 1, you don't have that issue. A block either exists or does not. Raghu 2009/10/5 Manhee Jo <[email protected]> > Hi all, > > Why isn't the dfs.safemode.threshold.pct 1 by default? > When dfs.replication.min=1 with dfs.safemode.threshold.pct=0.999, > there might be chances for a NameNode to check in with incomplete data > in its file system. Am I right? Is it permissible? Or is it assuming that > replication would be always more than 1? > > > Thanks, > Manhee
