5.3. Known Issues for HBase

Local short circuit reads (SSR) in Hadoop 2 allocates direct buffers, which may cause Out of Memory issues if the total number of stored files in the RegionServer grows large.
Suggested workarounds are as listed below:
- Turn off SSR for Hadoop 2.
- Ensure that there is enough unallocated memory for the RegionServer based on expected number of stored files.
- Ensure that the number of regions per RegionServer (hence number of open files) are low.
Fore more details, see HBASE-8143
For HBase, ReplicationZookeeper.copyQueuesFromRSUsingMulti returns queues when it fails to execute. For more details, see HBASE-8099.
The workaround is to disable the hbase.zookeeper.useMulti property.