[HDFS-4420] Provide a way to exclude subtree from balancing process

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Duplicate
• Component/s: balancer & mover
• Assignee: Unassigned
• Reporter: Max Lapan
• Created: 18/Jan/13 12:26
• Updated: 24/Jul/18 12:55
• Resolved: 24/Mar/15 19:31

Description

During balancer operation, it balances all blocks, regardless of their filesystem hierarchy. Sometimes, it would be usefull to exclude some subtree from balancing process.

For example, regionservers data locality is cruical for HBase performance. Region's data is tied to regionservers, which reside on specific machines in cluster. During operation, regionservers reads and writes region's data, and after some time, all this data are reside on local machine, so, all reads become local, which is great for performance. Balancer breaks this locality during opertation by moving blocks around.

This patch adds [-exclude <path>] switch, and, if path is provided,
balancer will not move blocks under this path during operation.

Attached patch have tested for 0.90.2.

Issue Links

• is duplicated by: HDFS-4509 Provide a way to ask Balancer to exclude certain DataNodes in its computation and/or work.
• is related to: HDFS-13763 HDFS Balancer - include path to only move blocks for a certain directory tree
• relates to: HDFS-6133 Add a feature for replica pinning so that a pinned replica will not be moved by Balancer/Mover.