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Date: Mon, 21 Jul 2014 18:14:39 +0000 (UTC)
From: "Allen Wittenauer (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12412634.1232144799236.11204.1405966479903@arcas>
In-Reply-To: <JIRA.12412634.1232144799236@arcas>
References: <JIRA.12412634.1232144799236@arcas>
Subject: [jira] [Comment Edited] (HDFS-125) Consistency of different
 replicas of the same block is not checked.
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    [ https://issues.apache.org/jira/browse/HDFS-125?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14068950#comment-14068950 ] 

Allen Wittenauer edited comment on HDFS-125 at 7/21/14 6:12 PM:
----------------------------------------------------------------

This feels like a special case of the problems mentioned in HDFS-366 and friends.


was (Author: aw):
This feels like a special case of the problems mentioned in HDFS-366 .

> Consistency of different replicas of the same block is not checked.
> -------------------------------------------------------------------
>
>                 Key: HDFS-125
>                 URL: https://issues.apache.org/jira/browse/HDFS-125
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Konstantin Shvachko
>
> HDFS currently detects corrupted replicas by verifying that its contents matches the checksum stored in the block meta-file. This is done independently for each replica of the block on the data-node it belongs to. But we do not check that the replicas are identical across data-nodes as long as they have the same size.
> This is not common but can happen as a result of a software bug or an operator mismanagement. And in this case different clients will read different data from the same file.


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