[HDFS-3475] Make the replication and invalidation rates configurable

• Type: Improvement
• Status: Closed
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 2.0.0-alpha
• Fix Version/s: 2.0.2-alpha
• Hadoop Flags: Reviewed

Release Note

This change adds two new configuration parameters.
# {{dfs.namenode.invalidate.work.pct.per.iteration}} for controlling deletion rate of blocks.
# {{dfs.namenode.replication.work.multiplier.per.iteration}} for controlling replication rate. This in turn allows controlling the time it takes for decommissioning.

Please see hdfs-default.xml for detailed description.

• Assignee: Harsh J
• Reporter: Harsh J
• Created: 30/May/12 12:03
• Updated: 11/Oct/12 17:46
• Resolved: 28/Jun/12 18:05

Description

BlockManager currently hardcodes the following two constants:

private static final int INVALIDATE_WORK_PCT_PER_ITERATION = 32;
private static final int REPLICATION_WORK_MULTIPLIER_PER_ITERATION = 2;

These are used to throttle/limit the amount of deletion and replication-to-other-DN work done per heartbeat interval of a live DN.

Not many have had reasons to want these changed so far but there have been a few requests I've faced over the past year from a variety of clusters I've helped maintain. I think with the improvements in disks and network thats already started to be rolled out in production environments out there, changing these may start making sense to some.

Lets at least make it advanced-configurable with proper docs that warn adequately, with the defaults being what they are today. With hardcodes, it comes down to a recompile for admins, which is not something they may like.

Please let me know your thoughts.

Issue Links

• Is contained by: HDFS-3814 Make the replication monitor multipliers configurable in 1.x
• relates to: HDFS-3816 Invalidate work percentage default value should be 0.32f instead of 32
• relates to: HDFS-3819 Should check whether invalidate work percentage default value is not greater than 1.0f