Index: src/docbkx/book.xml =================================================================== --- src/docbkx/book.xml (revision 1214613) +++ src/docbkx/book.xml (working copy) @@ -1319,6 +1319,8 @@ Startup Sequencing The META location is set in ROOT first. Then META is updated with server and startcode values. + For information on region-RegionServer assignment, see . + @@ -1724,46 +1726,35 @@
Startup When HBase starts regions are assigned as follows (short version): - - - The Master invokes the AssignmentManager upon startup. + The Master invokes the AssignmentManager upon startup. - - The AssignmentManager looks at the existing region assignments - in META. + The AssignmentManager looks at the existing region assignments in META. - - If the region assignment is still valid (i.e., if the RegionServer) is still online + If the region assignment is still valid (i.e., if the RegionServer) is still online then the assignment is kept. - - - If the assignment is invalid, then the LoadBalancerFactory is invoked to assign the - region. The DefaultLoadBalancer will randomly assign the region to a RegionServer. - + If the assignment is invalid, then the LoadBalancerFactory is invoked to assign the + region. The DefaultLoadBalancer will randomly assign the region to a RegionServer and + update META. - - + +
Failover When a RegionServer fails (short version): - - - The regions immediately become unavailable because the RegionServer is down. + The regions immediately become unavailable because the RegionServer is down. - - The Master will detect that the RegionServer has failed. + The Master will detect that the RegionServer has failed. - - The region assignments will be considered invalid and will be re-assigned just + The region assignments will be considered invalid and will be re-assigned just like the startup sequence. - +
@@ -1784,9 +1775,9 @@ First replica is written to local node - Second replica to another node in same rack + Second replica is written to another node in same rack - Third replica to a node in another rack (if sufficient nodes) + Third replica is written to a node in another rack (if sufficient nodes) HBase eventually achieves locality for a region after a flush a compaction.