Mailing-List: contact hadoop-dev-help@lucene.apache.org; run by ezmlm
Precedence: bulk
Reply-To: hadoop-dev@lucene.apache.org
Message-ID: <5882826.1180997306301.JavaMail.jira@brutus>
Date: Mon, 4 Jun 2007 15:48:26 -0700 (PDT)
From: "Jim Kellerman (JIRA)" <jira@apache.org>
To: hadoop-dev@lucene.apache.org
Subject: [jira] Commented: (HADOOP-1421) When a region server dies, its log
 must be distributed to all the new servers that have been assigned its
 regions
In-Reply-To: <31536774.1179876496145.JavaMail.jira@brutus>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/HADOOP-1421?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12501399 ] 

Jim Kellerman commented on HADOOP-1421:
---------------------------------------

On a  clean shutdown, each region is closed by the HRegionServer.

The steps of closing a region are:
1. flush memcache to HLog
2. flush the HStores. This has the effect of creating a new HStoreFile from the memcache flush and consequently, the HLog should be empty if the shutdown completes cleanly.

Consequently, the only case in which we need to read and split the HLog occurs when a HRegionServer dies. Since this is only known to the master, the master can do the HLog splitting while it is looking for the regions that the downed region server was serving.

> When a region server dies, its log must be distributed to all the new servers that have been assigned its regions
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-1421
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1421
>             Project: Hadoop
>          Issue Type: New Feature
>          Components: contrib/hbase
>            Reporter: Jim Kellerman
>            Assignee: Jim Kellerman
>
> When a region server dies, the master reallocates all the regions it was serving to other region servers. In order for the regions to be recovered properly, the log from the old region server must be split up into chunks that contain only the commits for a single region.
> Ideally, if a region server is assigned more than one of the old servers regions, the log for that server would contain all the commits for all the regions it has been assigned.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.