Return-Path: X-Original-To: apmail-hadoop-hdfs-user-archive@minotaur.apache.org Delivered-To: apmail-hadoop-hdfs-user-archive@minotaur.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 7B152FF10 for ; Thu, 18 Apr 2013 19:46:05 +0000 (UTC) Received: (qmail 54925 invoked by uid 500); 18 Apr 2013 19:46:00 -0000 Delivered-To: apmail-hadoop-hdfs-user-archive@hadoop.apache.org Received: (qmail 54636 invoked by uid 500); 18 Apr 2013 19:46:00 -0000 Mailing-List: contact user-help@hadoop.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@hadoop.apache.org Delivered-To: mailing list user@hadoop.apache.org Received: (qmail 54629 invoked by uid 99); 18 Apr 2013 19:46:00 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 18 Apr 2013 19:46:00 +0000 X-ASF-Spam-Status: No, hits=1.5 required=5.0 tests=HTML_FONT_SIZE_LARGE,HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of dechouxb@gmail.com designates 209.85.215.45 as permitted sender) Received: from [209.85.215.45] (HELO mail-la0-f45.google.com) (209.85.215.45) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 18 Apr 2013 19:45:54 +0000 Received: by mail-la0-f45.google.com with SMTP id gw10so2939400lab.32 for ; Thu, 18 Apr 2013 12:45:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=/17x3PMMCCc3yc06T/HMMDc5qyW76tQShyyU6dgTtX0=; b=QLUow88GbjBIqeE9dycRsk/aKb1CVAQyO2rRPPYVyTf4Y0jenPwJB26qfT876/VPXL hZI2ZUpvPMluQdTlQBGESU1pW+X37L+VwrrjiJQzrMk6uVTJmkP2uow86D2vpr/V0eCG kY3Ii1wXGYwRIPJXLn7IrL6M91dR/p6JD1FucdKvAGpoearTigr5ZtvZtap3MCWY4Ghw egDn0htb/0x5mB5oTSwan8D8Wb97kmi7Q2mT7gwrkWtLPOBbLbJMouX2bquc1KmOBau9 k7r+Y/igTxh8swGa8JKQJuhlG38y7gzdwMTtay7iOiYE65OYOrr7bBy2FrDLF2TkhrXH Qvjg== MIME-Version: 1.0 X-Received: by 10.112.209.38 with SMTP id mj6mr6016226lbc.52.1366314334024; Thu, 18 Apr 2013 12:45:34 -0700 (PDT) Received: by 10.112.34.230 with HTTP; Thu, 18 Apr 2013 12:45:33 -0700 (PDT) In-Reply-To: References: Date: Thu, 18 Apr 2013 21:45:33 +0200 Message-ID: Subject: Re: why multiple checkpoint nodes? From: Bertrand Dechoux To: "user@hadoop.apache.org" Content-Type: multipart/alternative; boundary=001a11c2622287fab604daa7d881 X-Virus-Checked: Checked by ClamAV on apache.org --001a11c2622287fab604daa7d881 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable It would be important to point the document (which I believe is http://hadoop.apache.org/docs/stable/hdfs_user_guide.html) and the version of Hadoop you are interested in. At one time, the documentation was misleading. The 1.x version didn't have checkpoint/backup nodes only the secondary namenode. I don't believe it has changed but I might be wrong (or the documentation still hasn't been fixed). The 2.x version will have namenode HA which will be the final solution. Regards Bertrand On Thu, Apr 18, 2013 at 7:20 PM, Thanh Do wrote: > so reliability (to prevent metadata loss) is the main motivation for > multiple checkpoint nodes? > > Does anybody use multiple checkpoint nodes in real life? > > Thanks > > > On Thu, Apr 18, 2013 at 12:07 PM, shashwat shriparv < > dwivedishashwat@gmail.com> wrote: > >> more checkpoint nodes means more backup of the metadata :) >> >> *Thanks & Regards * >> >> =E2=88=9E >> Shashwat Shriparv >> >> >> >> On Thu, Apr 18, 2013 at 9:35 PM, Thanh Do wrote: >> >>> Hi all, >>> >>> The document says "Multiple checkpoint nodes may be specified in the >>> cluster configuration file". >>> >>> Can some one clarify me that why we really need to run multiple >>> checkpoint nodes anyway? Is it possible that while checkpoint node A is >>> doing checkpoint, and check point node B kicks in and does another >>> checkpoint? >>> >>> Thanks, >>> Thanh >>> >> >> > --=20 Bertrand Dechoux --001a11c2622287fab604daa7d881 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
It would be important to point the document (whi= ch I believe is http://hadoop.apache.org/docs/stable/hdfs_user_guide.html) a= nd the version of Hadoop you are interested in. At one time, the documentat= ion was misleading. The 1.x version didn't have checkpoint/backup nodes= only the secondary namenode. I don't believe it has changed but I migh= t be wrong (or the documentation still hasn't been fixed). The 2.x vers= ion will have namenode HA which will be the final solution.

Regards

Bertrand


On Thu, Apr 18, 2013 at 7:20 PM, Thanh = Do <thanhdo@cs.wisc.edu> wrote:
so reliability (to prevent = metadata loss) is the main motivation for multiple checkpoint nodes?
Does anybody use multiple checkpoint nodes in real life?

Thanks

On Thu, Apr 18, 2013 at 12:07 PM, shashwat= shriparv <dwivedishashwat@gmail.com> wrote:
more checkpoint nodes means= more backup of the metadata :)

Thanks & Regards =C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=20 =09 =09 =09 =09

<= font size=3D"6">=E2=88=9E

Shash= wat Shriparv

<= div>


On Thu, Apr 18, 2013 at 9:35 PM, Thanh D= o <thanhdo@cs.wisc.edu> wrote:
Hi all,

The document says &qu= ot;Multiple checkpoint nodes may be specified in the cluster = configuration file".

Can some one clarify= me that why we really need to run multiple checkpoint nodes anyway? Is it = possible that while checkpoint node A is doing checkpoint, and check point = node B kicks in and does another checkpoint?

Thanks,
Thanh





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Bertrand De= choux --001a11c2622287fab604daa7d881--