[HBASE-7932] Do the necessary plumbing for the region locations in META table and send the info to the RegionServers

• Type: Sub-task
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 0.95.1

Release Note

Introduces "favored nodes" for region files. Has an implementation of LoadBalancer that assigns favored nodes for each region. There is a Primary RegionServer that hosts the region, and then there is Secondary and Tertiary RegionServers. Currently, the favored nodes information is used in creating HDFS files - the Primary RegionServer passes the primary, secondary, tertiary node addresses as hints to the DistributedFileSystem API for creating files on the filesystem. These nodes are treated as hints by the HDFS to place the blocks of the file (this will be complete when HBASE-7942 is addressed). This alleviates the problem to do with reading from remote nodes (since we can make the Secondary RegionServer as the new Primary RegionServer) after a region is recovered. This should help provide consistent read latencies for the regions even when their primary region servers die. The implementation of the balancer is not complete as of this issue.

• Tags: 0.96notable
• Assignee: Devaraj Das
• Reporter: Devaraj Das
• Created: 25/Feb/13 21:48
• Updated: 06/Aug/18 11:01
• Resolved: 12/May/13 07:01

Description

To be specific, this jira is to do the following during createTable:
1. Favored node calculation
2. Persisting of calculation in .META.
3. Letting RegionServers know of the favored nodes for new regions
4. Addition of a balancer that will honor favored nodes but it is currently a noop.

Issue Links

• blocks: HBASE-7942 Make use of the plumbing in HBASE-7932 to provide location hints when region files are created
• is related to: HBASE-21014 Improve Stochastic Balancer to write HDFS favoured node hints for region primary blocks to avoid destroying data locality if needing to use HDFS Balancer
• relates to: HBASE-17760 HDFS Balancer doc is misleading