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Edit of the decommisioning nodes section 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1491070 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Michael Stack 2013-06-08 21:38:37 +00:00
parent a9270d385b
commit ae4af86f5a
1 changed files with 17 additions and 10 deletions
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27
src/main/docbkx/ops_mgt.xml
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@ -417,29 +417,35 @@ This turns the balancer OFF. To reenable, do:
false
0 row(s) in 0.3590 seconds</programlisting>
</para>
<para>The <command>graceful_stop</command> will check the balancer
and if enabled, will turn it off before it goes to work. If it
exits prematurely because of error, it will not have reset the
balancer. Hence, it is better to manage the balancer apart from
<command>graceful_stop</command> reenabling it after you are done
w/ graceful_stop.
</para>
</note>
</para>
<section xml:id="draining.servers">
<title>Decommissioning several Regions Servers concurrently</title>
<para>If you have a large cluster, you may want to
decomission more than one machines at a time by gracefully
decommission more than one machine at a time by gracefully
stopping mutiple RegionServers concurrently.
</para>
<para>To gracefully drain multiple regionservers at the
To gracefully drain multiple regionservers at the
same time, RegionServers can be put into a "draining"
state. This is done by marking a RegionServer as a
draining node by creating an entry in ZooKeeper under the
hbase_root/draining znode. This znode has format
"name,port,startcode" just like the regionserver entries
under hbase_root/rs znode.
<filename>hbase_root/draining</filename> znode. This znode has format
<programlisting>name,port,startcode</programlisting> just like the regionserver entries
under <filename>hbase_root/rs</filename> znode.
</para>
<para>Without this, when decommissioning mulitple nodes
<para>Without this facility, decommissioning mulitple nodes
may be non-optimal because regions that are being drained
from one region server may be moved to other regions that
from one region server may be moved to other regionservers that
are also draining. Marking RegionServers to be in the
draining state prevents this from happening. <note>See
draining state prevents this from happening<footnote><para>See
this <link xlink:href="http://inchoate-clatter.blogspot.com/2012/03/hbase-ops-automation.html">blog
post</link> for more details. </note>
post</link> for more details.</para></footnote>.
</para>
</section>
@ -456,6 +462,7 @@ false
throw some errors in its logs as it recalibrates where to get its data from -- it will likely
roll its WAL log too -- but in general but for some latency spikes, it should keep on chugging.
<note>
<title>Short Circuit Reads</title>
<para>If you are doing short-circuit reads, you will have to move the regions off the regionserver
before you stop the datanode; when short-circuiting reading, though chmod'd so regionserver cannot
have access, because it already has the files open, it will be able to keep reading the file blocks