From user-return-3327-apmail-hadoop-user-archive=hadoop.apache.org@hadoop.apache.org Sat Dec 1 04:25:48 2012 Return-Path: X-Original-To: apmail-hadoop-user-archive@minotaur.apache.org Delivered-To: apmail-hadoop-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 B72F0E1C1 for ; Sat, 1 Dec 2012 04:25:48 +0000 (UTC) Received: (qmail 70088 invoked by uid 500); 1 Dec 2012 04:25:43 -0000 Delivered-To: apmail-hadoop-user-archive@hadoop.apache.org Received: (qmail 69890 invoked by uid 500); 1 Dec 2012 04:25:43 -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 69869 invoked by uid 99); 1 Dec 2012 04:25:42 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 01 Dec 2012 04:25:42 +0000 X-ASF-Spam-Status: No, hits=-0.7 required=5.0 tests=RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of harsh@cloudera.com designates 209.85.223.177 as permitted sender) Received: from [209.85.223.177] (HELO mail-ie0-f177.google.com) (209.85.223.177) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 01 Dec 2012 04:25:36 +0000 Received: by mail-ie0-f177.google.com with SMTP id k13so1666177iea.36 for ; Fri, 30 Nov 2012 20:25:15 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type:x-gm-message-state; bh=aiVijLBJl0218cq1I7P+3moy4V9IddU0Sq2CxpVmDAQ=; b=WOLq1i/UlxiLm6GL5hFVL0/zC/sYkQWoTt56uiEZOyJ8zWWDu5lrqDi+AAjpJzijY9 XXShze1KWpuk9SoaKCmUJUjQbdL9cvfVgF0EQ/jvVYpywuez0wix+CwwGVbUzp4memaj uy0qm/BNzPLdz7lN99SSlHR7ObOfSj5LGTkB+lq84oAewzPGATLSGWW9nYCjbcxq7Ydi wLrnE5MRONOHDuDtzH30wIFjluf9bK0qhlZrQ66SbtMaTpyF1HmMvpfPRbsrHxYWWxlU Ecuz6zMDSi5ODPqbp8u1+WcjXcnQp+xjjJkDu7oKLGEoHKo5jwZNvbxXcEMg+uCYZmGs VNXQ== Received: by 10.50.153.137 with SMTP id vg9mr451215igb.40.1354335915588; Fri, 30 Nov 2012 20:25:15 -0800 (PST) MIME-Version: 1.0 Received: by 10.64.6.129 with HTTP; Fri, 30 Nov 2012 20:24:55 -0800 (PST) In-Reply-To: References: From: Harsh J Date: Sat, 1 Dec 2012 09:54:55 +0530 Message-ID: Subject: Re: CheckPoint Node To: "" Content-Type: text/plain; charset=ISO-8859-1 X-Gm-Message-State: ALoCoQm17apUKOFYC6VSV/0lkoXTpQEZBqfDcFMySsV0wNt7HxFrXiP91Hq1gBpFZZCTFMrDfHJM X-Virus-Checked: Checked by ClamAV on apache.org Hi, On your question of how you may see configured values, I went over some ways for Andy previously here: http://search-hadoop.com/m/cmcAQ1FlzFp On Sat, Dec 1, 2012 at 7:55 AM, Jean-Marc Spaggiari wrote: > Sorry about that. My fault. > > I have put this on the core-site.xml file but should be on the hdfs-site.xml... > > I moved it and it's now working fine. > > Thanks. > > JM > > 2012/11/30, Jean-Marc Spaggiari : >> Hi, >> >> Is there a way to ask Hadoop to display its parameters? >> >> I have updated the property as followed: >> >> dfs.name.dir >> ${hadoop.tmp.dir}/dfs/name,/media/usb0/ >> >> >> But even if I stop/start hadoop, there is nothing written on the usb >> drive. So I'm wondering if there is a command line like bin/hadoop >> --showparameters >> >> Thanks, >> >> JM >> >> 2012/11/22, Jean-Marc Spaggiari : >>> Perfect. Thanks again for your time! >>> >>> I will first add another drive on the Namenode because this will take >>> 5 minutes. Then I will read about the migration from 1.0.3 to 2.0.x >>> and most probably will use the zookeeper solution. >>> >>> This will take more time, so will be done over the week-end. >>> >>> I lost 2 hard drives this week (2 datanodes), so I'm not a bit >>> concerned about the NameNode data. Just want to secure that a bit >>> more. >>> >>> JM >>> >>> 2012/11/22, Harsh J : >>>> Jean-Marc (Sorry if I've been spelling your name wrong), >>>> >>>> 0.94 does support Hadoop-2 already, and works pretty well with it, if >>>> that is your only concern. You only need to use the right download (or >>>> if you compile, use the -Dhadoop.profile=23 maven option). >>>> >>>> You will need to restart the NameNode to make changes to the >>>> dfs.name.dir property and set it into effect. A reasonably fast disk >>>> is needed for quicker edit log writes (few bytes worth in each round) >>>> but a large, or SSD-style disk is not a requisite. An external disk >>>> would work fine too (instead of an NFS), as long as it is reliable. >>>> >>>> You do not need to copy data manually - just ensure that your NameNode >>>> process user owns the directory and it will auto-populate the empty >>>> directory on startup. >>>> >>>> Operationally speaking, in case 1/2 disk fails, the NN Web UI (and >>>> metrics as well) will indicate this (see bottom of NN UI page for an >>>> example of what am talking about) but the NN will continue to run with >>>> the lone remaining disk, but its not a good idea to let it run for too >>>> long without fixing/replacing the disk, for you will be losing out on >>>> redundancy. >>>> >>>> On Thu, Nov 22, 2012 at 11:59 PM, Jean-Marc Spaggiari >>>> wrote: >>>>> Hi Harsh, >>>>> >>>>> Again, thanks a lot for all those details. >>>>> >>>>> I read the previous link and I totally understand the HA NameNode. I >>>>> already have a zookeeper quorum (3 servers) that I will be able to >>>>> re-use. However, I'm running HBase 0.94.2 which is not yet compatible >>>>> (I think) with Hadoop 2.0.x. So I will have to go with a non-HA >>>>> NameNode until I can migrate to a stable 0.96 HBase version. >>>>> >>>>> Can I "simply" add one directory to dfs.name.dir and restart >>>>> my namenode? Is it going to feed all the required information in this >>>>> directory? Or do I need to copy the data of the existing one in the >>>>> new one before I restart it? Also, does it need a fast transfert rate? >>>>> Or will an exteral hard drive (quick to be moved to another server if >>>>> required) be enought? >>>>> >>>>> >>>>> 2012/11/22, Harsh J : >>>>>> Please follow the tips provided at >>>>>> http://wiki.apache.org/hadoop/FAQ#How_do_I_set_up_a_hadoop_node_to_use_multiple_volumes.3Fand >>>>>> http://wiki.apache.org/hadoop/FAQ#If_the_NameNode_loses_its_only_copy_of_the_fsimage_file.2C_can_the_file_system_be_recovered_from_the_DataNodes.3F >>>>>> >>>>>> In short, if you use a non-HA NameNode setup: >>>>>> >>>>>> - Yes the NN is a very vital persistence point in running HDFS and its >>>>>> data should be redundantly stored for safety. >>>>>> - You should, in production, configure your NameNode's image and edits >>>>>> disk (dfs.name.dir in 1.x+, or dfs.namenode.name.dir in 0.23+/2.x+) to >>>>>> be a dedicated one with adequate free space for gradual growth, and >>>>>> should configure multiple disks (with one off-machine NFS point highly >>>>>> recommended for easy recovery) for adequate redundancy. >>>>>> >>>>>> If you instead use a HA NameNode setup (I'd highly recommend doing >>>>>> this since it is now available), the presence of > 1 NameNodes and the >>>>>> journal log mount or quorum setup would automatically act as >>>>>> safeguards for the FS metadata. >>>>>> >>>>>> On Thu, Nov 22, 2012 at 11:03 PM, Jean-Marc Spaggiari >>>>>> wrote: >>>>>>> Hi Harsh, >>>>>>> >>>>>>> Thanks for pointing me to this link. I will take a close look at it. >>>>>>> >>>>>>> So with 1.x and 0.23.x, what's the impact on the data if the namenode >>>>>>> server hard-drive die? Is there any critical data stored locally? Or >>>>>>> I >>>>>>> simply need to build a new namenode, start it and restart all my >>>>>>> namenodes to find my data back? >>>>>>> >>>>>>> I can deal with my application not beeing available, but loosing data >>>>>>> can be a bigger issue. >>>>>>> >>>>>>> Thanks, >>>>>>> >>>>>>> JM >>>>>>> >>>>>>> 2012/11/22, Harsh J : >>>>>>>> Hey Jean, >>>>>>>> >>>>>>>> The 1.x, 0.23.x release lines both don't have NameNode HA features. >>>>>>>> The current 2.x releases carry HA-NN abilities, and this is >>>>>>>> documented >>>>>>>> at >>>>>>>> http://hadoop.apache.org/docs/current/hadoop-yarn/hadoop-yarn-site/HDFSHighAvailability.html. >>>>>>>> >>>>>>>> On Thu, Nov 22, 2012 at 10:18 PM, Jean-Marc Spaggiari >>>>>>>> wrote: >>>>>>>>> Replying to myself ;) >>>>>>>>> >>>>>>>>> By digging a bit more I figured that 1.0 version is older than >>>>>>>>> 0.23.4 >>>>>>>>> version and that backupnodes are on 0.23.4. Secondarynamenodes on >>>>>>>>> 1.0 >>>>>>>>> are now deprecated. >>>>>>>>> >>>>>>>>> I'm still a bit mixed up on the way to achieve HA for the namenode >>>>>>>>> (1.0 or 0.23.4) but I will continue to dig over internet. >>>>>>>>> >>>>>>>>> JM >>>>>>>>> >>>>>>>>> 2012/11/22, Jean-Marc Spaggiari : >>>>>>>>>> Hi, >>>>>>>>>> >>>>>>>>>> I'm reading a bit about hadoop and I'm trying to increase the HA >>>>>>>>>> of >>>>>>>>>> my >>>>>>>>>> current cluster. >>>>>>>>>> >>>>>>>>>> Today I have 8 datanodes and one namenode. >>>>>>>>>> >>>>>>>>>> By reading here: http://www.aosabook.org/en/hdfs.html I can see >>>>>>>>>> that >>>>>>>>>> a >>>>>>>>>> Checkpoint node might be a good idea. >>>>>>>>>> >>>>>>>>>> So I'm trying to start a checkpoint node. I looked at the hadoop >>>>>>>>>> online doc. There is a link toe describe the command usage "For >>>>>>>>>> command usage, see namenode." but this link is not working. Also, >>>>>>>>>> if >>>>>>>>>> I >>>>>>>>>> try hadoop-deamon.sh start namenode -checkpoint as discribed in >>>>>>>>>> the >>>>>>>>>> documentation, it's not starting. >>>>>>>>>> >>>>>>>>>> So I'n wondering, is there anywhere where I can find up to date >>>>>>>>>> documentation about the checkpoint node? I will most probably try >>>>>>>>>> the >>>>>>>>>> BackupNode. >>>>>>>>>> >>>>>>>>>> I'm using hadoop 1.0.3. The options I have to start on this >>>>>>>>>> version >>>>>>>>>> are namenode, secondarynamenode, datanode, dfsadmin, mradmin, fsck >>>>>>>>>> and >>>>>>>>>> fs. Should I start some secondarynamenodes instead of backupnode >>>>>>>>>> and >>>>>>>>>> checkpointnode? >>>>>>>>>> >>>>>>>>>> Thanks, >>>>>>>>>> >>>>>>>>>> JM >>>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Harsh J >>>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Harsh J >>>>>> >>>> >>>> >>>> >>>> -- >>>> Harsh J >>>> >>> >> -- Harsh J