Mailing-List: contact hdfs-issues-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: hdfs-issues@hadoop.apache.org
Date: Thu, 3 Nov 2011 17:25:32 +0000 (UTC)
From: "Robert Chansler (Updated) (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: 
 <722926759.56493.1320341132823.JavaMail.tomcat@hel.zones.apache.org>
In-Reply-To: 
 <487762836.56485.1320341132411.JavaMail.tomcat@hel.zones.apache.org>
Subject: [jira] [Updated] (HDFS-2535) A Model for Data Durability
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


     [ https://issues.apache.org/jira/browse/HDFS-2535?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Chansler updated HDFS-2535:
----------------------------------

    Attachment: LosingBlocks.xlsx

Model Spreadsheet
                
> A Model for Data Durability
> ---------------------------
>
>                 Key: HDFS-2535
>                 URL: https://issues.apache.org/jira/browse/HDFS-2535
>             Project: Hadoop HDFS
>          Issue Type: Task
>          Components: documentation
>            Reporter: Robert Chansler
>            Assignee: Robert Chansler
>         Attachments: LosingBlocks.xlsx
>
>
> This is a statistical model considering data durability in HDFS in the presence of Data Node failures. The attached spreadsheet considers the probability of losing a block with three replicas in the case of uncorrelated failures of DNs. Also included is a section that looks at the consequences of simultaneous failures. 
> The model parameters reflect experience at Yahoo with a large cluster. But it is easy to change the parameters in the spreadsheet. Number of replicas is not a easily adjusted parameter. And while published reports (the Google papers) suggest that node failures are not really uncorrelated, this does give some practical insight into HDFS durability.
> I and others have quoted from this work in the past. I thought it good to make the details conveniently available.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira