Return-Path: X-Original-To: apmail-hadoop-common-user-archive@www.apache.org Delivered-To: apmail-hadoop-common-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 25B8111BC4 for ; Sat, 11 May 2013 17:17:37 +0000 (UTC) Received: (qmail 62052 invoked by uid 500); 11 May 2013 17:17:31 -0000 Delivered-To: apmail-hadoop-common-user-archive@hadoop.apache.org Received: (qmail 61688 invoked by uid 500); 11 May 2013 17:17:31 -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 61680 invoked by uid 99); 11 May 2013 17:17:31 -0000 Received: from athena.apache.org (HELO athena.apache.org) (140.211.11.136) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 11 May 2013 17:17:31 +0000 X-ASF-Spam-Status: No, hits=2.5 required=5.0 tests=FREEMAIL_REPLY,HTML_MESSAGE,RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (athena.apache.org: domain of rahul.rec.dgp@gmail.com designates 209.85.128.174 as permitted sender) Received: from [209.85.128.174] (HELO mail-ve0-f174.google.com) (209.85.128.174) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 11 May 2013 17:17:26 +0000 Received: by mail-ve0-f174.google.com with SMTP id pb11so4748809veb.33 for ; Sat, 11 May 2013 10:17:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:mime-version:in-reply-to:references:from:date:message-id :subject:to:content-type; bh=/83cFR+CiV5QzYGATTcfEcTM40N1EeBna5W+WTOsrSQ=; b=bbRQvLhTQeyP+33n21srsWvmTG2GTJy9bdYBn1GwVBYnSAo00cgaWaM+HjTL5SP2P+ SFagBrR7sRPMA4cLkCElR0gLyioTH0Ezz3h10qx8cITiM8mqZC5aLQCaZ27Y1OK9Ahql zBUDGmeMrZP0VmvNmEH7yDZFoNCA9/cgjGguCuf9HDVA9N6OVL0O8tJOZBzyGQwhWH4z dQbwTlP/KsPTYgN16t3olZi9k9RrXACYXvahLKJe2FTgmqzK4Mk9UdzQZqDbtUFBckTJ W6VZ5+8z5xzuW8UYouZjMbhdZ403QnF0ePkYjNYmkOo+IDfFGm8XRWjBeBrW9t1hOJFK aBDw== X-Received: by 10.52.156.232 with SMTP id wh8mr10620689vdb.103.1368292625100; Sat, 11 May 2013 10:17:05 -0700 (PDT) MIME-Version: 1.0 Received: by 10.59.6.68 with HTTP; Sat, 11 May 2013 10:16:45 -0700 (PDT) In-Reply-To: References: From: Rahul Bhattacharjee Date: Sat, 11 May 2013 22:46:45 +0530 Message-ID: Subject: Re: Hadoop noob question To: "user@hadoop.apache.org" Content-Type: multipart/alternative; boundary=089e01633aa8de366a04dc74737f X-Virus-Checked: Checked by ClamAV on apache.org --089e01633aa8de366a04dc74737f Content-Type: text/plain; charset=UTF-8 Thanks Tariq! On Sat, May 11, 2013 at 10:34 PM, Mohammad Tariq wrote: > @Rahul : Yes. distcp can do that. > > And, bigger the files lesser the metadata hence lesser memory consumption. > > Warm Regards, > Tariq > cloudfront.blogspot.com > > > On Sat, May 11, 2013 at 9:40 PM, Rahul Bhattacharjee < > rahul.rec.dgp@gmail.com> wrote: > >> IMHO,I think the statement about NN with regard to block metadata is more >> like a general statement. Even if you put lots of small files of combined >> size 10 TB , you need to have a capable NN. >> >> can disct cp be used to copy local - to - hdfs ? >> >> Thanks, >> Rahul >> >> >> On Sat, May 11, 2013 at 9:35 PM, Nitin Pawar wrote: >> >>> absolutely rite Mohammad >>> >>> >>> On Sat, May 11, 2013 at 9:33 PM, Mohammad Tariq wrote: >>> >>>> Sorry for barging in guys. I think Nitin is talking about this : >>>> >>>> Every file and block in HDFS is treated as an object and for each >>>> object around 200B of metadata get created. So the NN should be powerful >>>> enough to handle that much metadata, since it is going to be in-memory. >>>> Actually memory is the most important metric when it comes to NN. >>>> >>>> Am I correct @Nitin? >>>> >>>> @Thoihen : As Nitin has said, when you talk about that much data you >>>> don't actually just do a "put". You could use something like "distcp" for >>>> parallel copying. A better approach would be to use a data aggregation tool >>>> like Flume or Chukwa, as Nitin has already pointed. Facebook uses their own >>>> data aggregation tool, called Scribe for this purpose. >>>> >>>> Warm Regards, >>>> Tariq >>>> cloudfront.blogspot.com >>>> >>>> >>>> On Sat, May 11, 2013 at 9:20 PM, Nitin Pawar wrote: >>>> >>>>> NN would still be in picture because it will be writing a lot of meta >>>>> data for each individual file. so you will need a NN capable enough which >>>>> can store the metadata for your entire dataset. Data will never go to NN >>>>> but lot of metadata about data will be on NN so its always good idea to >>>>> have a strong NN. >>>>> >>>>> >>>>> On Sat, May 11, 2013 at 9:11 PM, Rahul Bhattacharjee < >>>>> rahul.rec.dgp@gmail.com> wrote: >>>>> >>>>>> @Nitin , parallel dfs to write to hdfs is great , but could not >>>>>> understand the meaning of capable NN. As I know , the NN would not be a >>>>>> part of the actual data write pipeline , means that the data would not >>>>>> travel through the NN , the dfs would contact the NN from time to time to >>>>>> get locations of DN as where to store the data blocks. >>>>>> >>>>>> Thanks, >>>>>> Rahul >>>>>> >>>>>> >>>>>> >>>>>> On Sat, May 11, 2013 at 4:54 PM, Nitin Pawar >>>>> > wrote: >>>>>> >>>>>>> is it safe? .. there is no direct answer yes or no >>>>>>> >>>>>>> when you say , you have files worth 10TB files and you want to >>>>>>> upload to HDFS, several factors come into picture >>>>>>> >>>>>>> 1) Is the machine in the same network as your hadoop cluster? >>>>>>> 2) If there guarantee that network will not go down? >>>>>>> >>>>>>> and Most importantly I assume that you have a capable hadoop >>>>>>> cluster. By that I mean you have a capable namenode. >>>>>>> >>>>>>> I would definitely not write files sequentially in HDFS. I would >>>>>>> prefer to write files in parallel to hdfs to utilize the DFS write features >>>>>>> to speed up the process. >>>>>>> you can hdfs put command in parallel manner and in my experience it >>>>>>> has not failed when we write a lot of data. >>>>>>> >>>>>>> >>>>>>> On Sat, May 11, 2013 at 4:38 PM, maisnam ns wrote: >>>>>>> >>>>>>>> @Nitin Pawar , thanks for clearing my doubts . >>>>>>>> >>>>>>>> But I have one more question , say I have 10 TB data in the >>>>>>>> pipeline . >>>>>>>> >>>>>>>> Is it perfectly OK to use hadopo fs put command to upload these >>>>>>>> files of size 10 TB and is there any limit to the file size using hadoop >>>>>>>> command line . Can hadoop put command line work with huge data. >>>>>>>> >>>>>>>> Thanks in advance >>>>>>>> >>>>>>>> >>>>>>>> On Sat, May 11, 2013 at 4:24 PM, Nitin Pawar < >>>>>>>> nitinpawar432@gmail.com> wrote: >>>>>>>> >>>>>>>>> first of all .. most of the companies do not get 100 PB of data in >>>>>>>>> one go. Its an accumulating process and most of the companies do have a >>>>>>>>> data pipeline in place where the data is written to hdfs on a frequency >>>>>>>>> basis and then its retained on hdfs for some duration as per needed and >>>>>>>>> from there its sent to archivers or deleted. >>>>>>>>> >>>>>>>>> For data management products, you can look at falcon which is open >>>>>>>>> sourced by inmobi along with hortonworks. >>>>>>>>> >>>>>>>>> In any case, if you want to write files to hdfs there are few >>>>>>>>> options available to you >>>>>>>>> 1) Write your dfs client which writes to dfs >>>>>>>>> 2) use hdfs proxy >>>>>>>>> 3) there is webhdfs >>>>>>>>> 4) command line hdfs >>>>>>>>> 5) data collection tools come with support to write to hdfs like >>>>>>>>> flume etc >>>>>>>>> >>>>>>>>> >>>>>>>>> On Sat, May 11, 2013 at 4:19 PM, Thoihen Maibam < >>>>>>>>> thoihen123@gmail.com> wrote: >>>>>>>>> >>>>>>>>>> Hi All, >>>>>>>>>> >>>>>>>>>> Can anyone help me know how does companies like Facebook ,Yahoo >>>>>>>>>> etc upload bulk files say to the tune of 100 petabytes to Hadoop HDFS >>>>>>>>>> cluster for processing >>>>>>>>>> and after processing how they download those files from HDFS to >>>>>>>>>> local file system. >>>>>>>>>> >>>>>>>>>> I don't think they might be using the command line hadoop fs put >>>>>>>>>> to upload files as it would take too long or do they divide say 10 parts >>>>>>>>>> each 10 petabytes and compress and use the command line hadoop fs put >>>>>>>>>> >>>>>>>>>> Or if they use any tool to upload huge files. >>>>>>>>>> >>>>>>>>>> Please help me . >>>>>>>>>> >>>>>>>>>> Thanks >>>>>>>>>> thoihen >>>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> -- >>>>>>>>> Nitin Pawar >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Nitin Pawar >>>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>>> -- >>>>> Nitin Pawar >>>>> >>>> >>>> >>> >>> >>> -- >>> Nitin Pawar >>> >> >> > --089e01633aa8de366a04dc74737f Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Thanks Tariq!


On Sat, May 11, 2013 at 10:= 34 PM, Mohammad Tariq <dontariq@gmail.com> wrote:
@Rahul : Yes. distcp can do= that.

And, bigger the files lesser the metadata hence l= esser memory consumption.

Wa= rm Regards,
Tariq


On Sat, May 11, 2013 at 9:40 PM, Rahul B= hattacharjee <rahul.rec.dgp@gmail.com> wrote:
IMHO,I think the statement about NN with regard to block met= adata is more like a general statement. Even if you put lots of small files= of combined size 10 TB , you need to have a capable NN.

can disct cp be used to copy local - to - hdfs ?

Thanks,
=
Rahul


On Sat, May 11, 2013 at 9:35 PM, Nitin Pawar <niti= npawar432@gmail.com> wrote:
absolutely rite Mohammad=C2= =A0


On Sat, May 11, 2013 at 9:33 PM, Mohammad Tariq <dontariq@gmail.com&g= t; wrote:
Sorry for barging in guys. = I think Nitin is talking about this :

Every file and blo= ck in HDFS is treated as an object and for each object around 200B of metad= ata get created. So the NN should be powerful enough to handle that much me= tadata, since it is going to be in-memory. Actually memory is the most impo= rtant metric when it comes to NN.=C2=A0

Am I correct @Nitin?

@Thoihen = : As Nitin has said, when you talk about that much data you don't actua= lly just do a "put". You could use something like "distcp&qu= ot; for parallel copying. A better approach would be to use a data aggregat= ion tool like Flume or Chukwa, as Nitin has already pointed. Facebook uses = their own data aggregation tool, called Scribe for this purpose.

Wa= rm Regards,
Tariq


On Sat, May 11, 2013 at 9:20 PM, Nitin P= awar <nitinpawar432@gmail.com> wrote:
NN would still be in picture because it will be writing a = lot of meta data for each individual file. so you will need a NN capable en= ough which can store the metadata for your entire dataset. Data will never = go to NN but lot of metadata about data will be on NN so its always good id= ea to have a strong NN.


On = Sat, May 11, 2013 at 9:11 PM, Rahul Bhattacharjee <rahul.rec.dgp@gma= il.com> wrote:
@Nitin , parallel dfs to writ= e to hdfs is great , but could not understand the meaning of capable NN. As= I know , the NN would not be a part of the actual data write pipeline , me= ans that the data would not travel through the NN , the dfs would contact t= he NN from time to time to get locations of DN as where to store the data b= locks.

Thanks,
Rahul



On Sat, May 1= 1, 2013 at 4:54 PM, Nitin Pawar <nitinpawar432@gmail.com> wrote:
is it safe? .. there is no = direct answer yes or no=C2=A0

when you say , you have fi= les worth 10TB files and you want to upload =C2=A0to HDFS, several factors = come into picture=C2=A0

1) Is the machine in the same network as your hadoop cluster= ?
2) If there guarantee that network will not go down?
=
and Most importantly I assume that you have a capable hadoop= cluster. By that I mean you have a capable namenode.=C2=A0

I would definitely not write files=C2=A0sequentially=C2= =A0in HDFS. I would prefer to write files in parallel=C2=A0to hdfs to utili= ze the DFS write features to speed up the process.=C2=A0
you can = hdfs put command in parallel manner and in my experience it has not failed = when we write a lot of data.=C2=A0


On Sat, May 11, 2013 at 4:38 PM, maisnam ns <maisnam.ns@gmail.com> wrote:
@Nitin Pawar= , thanks for clearing my doubts .

But I have one more questio= n , say I have 10 TB data in the pipeline .

Is it perfectly OK to use hadopo fs put command to upload these f= iles of size 10 TB and is there any limit to the file size=C2=A0 using hado= op command line . Can hadoop put command line work with huge data.

Thanks in advance
<= br>
On Sat, May 11, 2013 at 4:24 PM, Nitin Pa= war <nitinpawar432@gmail.com> wrote:
first of all .. most of the= companies do not get 100 PB of data in one go. Its an accumulating process= and most of the companies do have a data pipeline in place where the data = is written to hdfs on a frequency basis and =C2=A0then its retained on hdfs= for some duration as per needed and from there its sent to archivers or de= leted.=C2=A0

For data management products, you can look at falcon which i= s open sourced by inmobi along with hortonworks.=C2=A0

=
In any case, if you want to write files to hdfs there are few options = available to you
1) Write your dfs client which writes to dfs
2) use hdfs pro= xy
3) there is webhdfs
4) command line hdfs
5= ) data collection tools come with support to write to hdfs like flume etc


On Sat, May 11, 2013 at 4:19 PM, Thoihen Maibam <thoihen123@gmail.co= m> wrote:
Hi All,

Can anyone help me know how does companies like Fac= ebook ,Yahoo etc upload bulk files say to the tune of 100 petabytes to Hado= op HDFS cluster for processing
and after processing how they download those files from HDFS to = local file system.

I don't think they might be = using the command line hadoop fs put to upload files as it would take too l= ong or do they divide say 10 parts each 10 petabytes and=C2=A0 compress and= use the command line hadoop fs put

Or if they use any tool to upload huge files.

Please= help me .

Thanks
thoihen



<= font color=3D"#888888">--
Nitin Pawar




<= /div>--
Nitin Pawar




<= /div>--
Nitin Pawar




<= font color=3D"#888888">--
Nitin Pawar



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