Hadoop V2 - Namenode Parameters

This blog covers details of Namenode and Namenode related parameters

Checkpoint Frequency

Checkpointing can be configured by setting

- dfs.namenode.checkpoint.period. This parameter controls the time between 2 checkpoints.
- dfs.namenode.checkpoint.txns. This parameter controls number of edit log transactions between 2 checkpoints.

 
Checkpoint Performance

- dfs.image.transfer.bandwidthPerSec. This parameter throttles B.W (bytes/sec) allowed for transferring Edit logs and FSImage during checkpointing process from namenode.
Default value is '0' which implies no throttling is done
   
- dfs.image.transfer.timeout - This parameter controls socket timeout (in milliseconds) for transferring Image
Default Value - 60,000 milliseconds

Safeguard Parameters 
 
- dfs.namenode.max.extra.edits.segments.retained. This control number of extra edit log segments whcih should be retained beyond what is required to restart namenode.
Default value - 10,000

- dfs.namenode.num.extra.edits.retained. This controls number of extra transactions to be retained beyond what is required to restart namenode
Default Value - 10,00,000