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Add doc of since removed hbase.bucketcache.percentage.in.combinedcache

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stack 2014-07-18 22:22:33 -07:00
parent 60d3e3c905
commit dcec55148e
1 changed files with 17 additions and 0 deletions
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src/main/docbkx/book.xml
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@ -2263,6 +2263,23 @@ rs.close();
<emphasis>Server Metrics: Memory</emphasis> tab in the UI. <emphasis>Server Metrics: Memory</emphasis> tab in the UI.
</para> </para>
</note> </note>
<note xml:id="hbase.bucketcache.percentage.in.combinedcache"><title>hbase.bucketcache.percentage.in.combinedcache</title>
<para>This is a pre-HBase 1.0 configuration removed because it
was confusing. It was a float that you would set to some value
between 0.0 and 1.0. Its default was 0.9. If the deploy was using
CombinedBlockCache, then the LruBlockCache L1 size was calculated to
be (1 - <varname>hbase.bucketcache.percentage.in.combinedcache</varname>) * <varname>size-of-bucketcache</varname>
and the BucketCache size was <varname>hbase.bucketcache.percentage.in.combinedcache</varname> * size-of-bucket-cache.
where size-of-bucket-cache itself is EITHER the value of the configuration hbase.bucketcache.size
IF it was specified as megabytes OR <varname>hbase.bucketcache.size</varname> * <varname>-XX:MaxDirectMemorySize</varname> if
<varname>hbase.bucketcache.size</varname> between 0 and 1.0.
</para>
<para>In 1.0, it should be more straight-forward. L1 LruBlockCache size
is set as a fraction of java heap using hfile.block.cache.size setting
(not the best name) and L2 is set as above either in absolute
megabytes or as a fraction of allocated maximum direct memory.
</para>
</note>
</section> </section>
</section> </section>
</section> </section>