diff --git a/src/main/asciidoc/_chapters/upgrading.adoc b/src/main/asciidoc/_chapters/upgrading.adoc index 489c36a8927..21ed65a9ee5 100644 --- a/src/main/asciidoc/_chapters/upgrading.adoc +++ b/src/main/asciidoc/_chapters/upgrading.adoc @@ -615,18 +615,35 @@ Performance is also an area that is now under active review so look forward to improvement in coming releases (See link:https://issues.apache.org/jira/browse/HBASE-20188[HBASE-20188 TESTING Performance]). -[[upgrade2.0.it.kerberos]] -.Integration Tests and Kerberos -Integration Tests (`IntegrationTests*`) used to rely on the Kerberos credential cache -for authentication against secured clusters. This used to lead to tests failing due -to authentication failures when the tickets in the credential cache expired. -As of hbase-2.0.0 (and hbase-1.3.0+), the integration test clients will make use -of the configuration properties `hbase.client.keytab.file` and -`hbase.client.kerberos.principal`. They are required. The clients will perform a -login from the configured keytab file and automatically refresh the credentials -in the background for the process lifetime (See -link:https://issues.apache.org/jira/browse/HBASE-16231[HBASE-16231]). +[[upgrade2.0.compaction.throughput.limit]] +.Default Compaction Throughput +HBase 2.x comes with default limits to the speed at which compactions can execute. This +limit is defined per RegionServer. In previous versions of HBase, there was no limit to +the speed at which a compaction could run by default. Applying a limit to the throughput of +a compaction should ensure more stable operations from RegionServers. +Take care to notice that this limit is _per RegionServer_, not _per compaction_. + +The throughput limit is defined as a range of bytes written per second, and is +allowed to vary within the given lower and upper bound. RegionServers observe the +current throughput of a compaction and apply a linear formula to adjust the allowed +throughput, within the lower and upper bound, with respect to external pressure. +For compactions, external pressure is defined as the number of store files with +respect to the maximum number of allowed store files. The more store files, the +higher the compaction pressure. + +Configuration of this throughput is governed by the following properties. + +- The lower bound is defined by `hbase.hstore.compaction.throughput.lower.bound` + and defaults to 10 MB/s (`10485760`). +- The upper bound is defined by `hbase.hstore.compaction.throughput.higher.bound` + and defaults to 20 MB/s (`20971520`). + +To revert this behavior to the unlimited compaction throughput of earlier versions +of HBase, please set the following property to the implementation that applies no +limits to compactions. + +`hbase.regionserver.throughput.controller=org.apache.hadoop.hbase.regionserver.throttle.NoLimitThroughputController` //// This would be a good place to link to an appendix on migrating applications