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https://issues.apache.org/jira/browse/HBASE-11717?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14092841#comment-14092841
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Sean Busbey commented on HBASE-11717:
-------------------------------------
If we're removing the SlabCache from the book, there are a couple of additional
references:
book.xml:
{code}
<section
xml:id="block.cache">
<title>Block Cache</title>
<para>HBase provides three different BlockCache implementations: the
default onheap
LruBlockCache, BucketCache, and SlabCache, which are both (usually)
offheap. This section
discusses benefits and drawbacks of each implementation, how to
choose the appropriate
option, and configuration options for each.</para>
<note><title>Block Cache Reporting: UI</title>
<para>See the RegionServer UI for detail on caching deploy. Since
HBase-0.98.4, the
Block Cache detail has been significantly extended showing
configurations,
sizings, current usage, and even detail on block counts and
types.</para>
</note>
<section>
<title>Cache Choices</title>
<para><classname>LruBlockCache</classname> is the original
implementation, and is
entirely within the Java heap. <classname>BucketCache</classname>
is mainly
intended for keeping blockcache data offheap, although
BucketCache can also
keep data onheap and serve from a file-backed cache. There is
also an older
offheap BlockCache, called SlabCache that has since been
deprecated and
removed in HBase 1.0.
</para>
{code}
At least the first reference should probably go.
> Remove unused config 'hbase.offheapcache.percentage' from hbase-default.xml
> and book
> ------------------------------------------------------------------------------------
>
> Key: HBASE-11717
> URL: https://issues.apache.org/jira/browse/HBASE-11717
> Project: HBase
> Issue Type: Bug
> Components: documentation
> Affects Versions: 2.0.0
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Priority: Trivial
> Fix For: 2.0.0
>
> Attachments: HBASE-11717.patch, HBASE-11717_V2.patch
>
>
> hbase.offheapcache.percentage is unused now.
> {code}
> <property>
> <name>hbase.offheapcache.percentage</name>
> <value>0</value>
> <description>The percentage of the off heap space
> (-XX:MaxDirectMemorySize) to be
> allocated towards the experimental off heap "SlabCache" (This is
> different to
> the BucketCache -- see the package javadoc for
> org.apache.hadoop.hbase.io.hfile
> for more on your options). If you desire the cache to be disabled,
> simply set this
> value to 0.</description>
> </property>
> {code}
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