Apache HBase 0.98.0 enables HBase administrators to configure their HBase clusters with read-only High Availability, or HA. This feature greatly benefits HBase applications that require low latency queries but can tolerate stale data, such as remote sensors, distributed messaging, object stores, and user profile management. HBase provides read-only HA on a per-table basis by replicating table regions with one or more secondary region servers. See Understanding Regions and RegionServers for more information.
HA for HBase features the following functionality:
Data safely protected in HDFS
Failed nodes are automatically recovered
No single point of failure
However, HBase administrators should carefully consider the the following costs associated with using secondary region servers:
Double or triple memstore usage
Increased block cache usage
Increased network traffic for log replication
Extra backup RPCs for replicas
Important | |
---|---|
This release of HA for HBase is not compatible with region splits and merges. Do not
execute region merges on tables with region replicas. Rather, HBase administrators must
split tables before enabling HA for HBase and disable region splits with the
|