[HBASE-18511] Default no regions on master

• Type: Task
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Component/s: master
• Hadoop Flags: Incompatible change

Release Note

Changes the configuration hbase.balancer.tablesOnMaster from list of table names that the can carry (with 'none' meaning no tables on the master) to instead be a boolean that is set to true if master carries tables/regions and false if it does not. If true, the master acts like any regionserver.

If false, then the master carries no tables. This is the default for hbase-2.0.0.

Another boolean configuration, hbase.balancer.tablesOnMaster.systemTablesOnly, when set to true, enables hbase.balancer.tablesOnMaster and makes it so the master hosts system tables exclusively (the long-time deploy mode of master branch and branch-2 up until this commit).

UPDATE: This is broke. See HBASE-19785.
UPDATE2: Master carrying Regions does not work reliably, see HBASE-19828.

See HBASE-19831, the issue to fix regions on Master

The change of hbase.balancer.tablesOnMaster from String list to boolean and
the addition of a simple boolean to enable system-tables on Master was done
to constrain what operators might ask for via this master configuration.
Stipulating what tables are bound to the Master server verges into
regionserver grouping territory, a more robust means of specifying table
and server combinations. Operators should use this latter if they want
layouts more exotic than those supplied by the provided booleans.

• Assignee: Michael Stack
• Reporter: Michael Stack
• Created: 03/Aug/17 05:47
• Updated: 19/Nov/19 01:33
• Resolved: 16/Aug/17 15:48

Description

Let this be umbrella issue for no-regions-on-master as default deploy (as it was in branch-1).

Also need to make sure we can run WITH regions on master; in particular system tables with RPC short-circuit as it is now in hbase master.

Background is that master branch carried a change that allowed Master carry regions. On top of this improvement on branch-1, Master defaulted to carry system tables only. No release was made with this configuration. Now we are going to cut the 2.0.0 release, the decision is that hbase-2 should have the same layout as hbase-1 so this issue implements the undoing of Master carrying system tables by default (though the capability remains).

Issue Links

• breaks: HBASE-18627 Fix TestRegionServerReadRequestMetrics
• breaks: HBASE-18634 Fix client.TestClientClusterStatus
• breaks: HBASE-18632 TestMultiParallel#testFlushCommitsWithAbort fails in master branch
• is depended upon by: HBASE-18543 Re-enable test master.TestMasterFailover on master
• is related to: HBASE-19831 Regions on the Master Redux
• relates to: HBASE-19785 System Regions on the Master is broken
• relates to: HBASE-18575 [AMv2] Enable and fix TestRestartCluster#testRetainAssignmentOnRestart on master
• relates to: HBASE-18551 [AMv2] UnassignProcedure and crashed regionservers
• links to: Review Board (master)

Sub-Tasks

• Test reenabling Master carrying regions: Resolved
• Clarify cryptic statement in Master#move: Open