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From "Adaryl \"Bob\" Wakefield, MBA" <adaryl.wakefi...@hotmail.com>
Subject Re: hadoop not using whole disk for HDFS
Date Sat, 07 Nov 2015 22:47:54 GMT
I think it might help if I had a better understanding of what I’m looking at:
      /dev/mapper/centos-home 2.7T 33M 2.7T 1% /home 


So /dev/mapper/centos-home is the file system and /home is where it is mounted. I’m not
sure I even know what that means. Are you saying that /hdfs/data even though it’s in root
that it’s still somehow pointing to /home? So confused. It’s the part amount mounting
a drive to another folder..on the same disk. Is it kind of like how on Windows you can have
more than one “drive” on a disk?

Adaryl "Bob" Wakefield, MBA
Principal
Mass Street Analytics, LLC
913.938.6685
www.linkedin.com/in/bobwakefieldmba
Twitter: @BobLovesData

From: Naganarasimha G R (Naga) 
Sent: Thursday, November 05, 2015 7:50 PM
To: user@hadoop.apache.org 
Subject: RE: hadoop not using whole disk for HDFS

Hi Bob,



1. I wasn’t able to set the config to /home/hdfs/data. I got an error that told me I’m
not allowed to set that config to the /home directory. So I made it /hdfs/data.

Naga : I am not sure about the HDP Distro but if you make it point to /hdfs/data, still it
will be pointing to the root mount itself i.e.

          /dev/mapper/centos-root 50G 12G 39G 23% / 


Other Alternative is to mount the drive to some other folder other than /home and then try.



2. When I restarted, the space available increased by a whopping 100GB.
Naga : I am particularly not sure how this happened may be you can again recheck if you enter
the command "df -h <path of the NM data dir configured>" you will find out how much
disk space is available on the related mount for which the path is configured.



Regards,

+ Naga








--------------------------------------------------------------------------------

From: Adaryl "Bob" Wakefield, MBA [adaryl.wakefield@hotmail.com]
Sent: Friday, November 06, 2015 06:54
To: user@hadoop.apache.org
Subject: Re: hadoop not using whole disk for HDFS


Is there a maximum amount of disk space that HDFS will use? Is 100GB that max? When we’re
supposed to be dealing with “big data” why is the amount of data to be held on any one
box such a small number when you’ve got terabytes available?

Adaryl "Bob" Wakefield, MBA
Principal
Mass Street Analytics, LLC
913.938.6685
www.linkedin.com/in/bobwakefieldmba
Twitter: @BobLovesData

From: Adaryl "Bob" Wakefield, MBA 
Sent: Wednesday, November 04, 2015 4:38 PM
To: user@hadoop.apache.org 
Subject: Re: hadoop not using whole disk for HDFS

This is an experimental cluster and there isn’t anything I can’t lose. I ran into some
issues. I’m running the Hortonworks distro and am managing things through Ambari. 

1. I wasn’t able to set the config to /home/hdfs/data. I got an error that told me I’m
not allowed to set that config to the /home directory. So I made it /hdfs/data.
2. When I restarted, the space available increased by a whopping 100GB.



Adaryl "Bob" Wakefield, MBA
Principal
Mass Street Analytics, LLC
913.938.6685
www.linkedin.com/in/bobwakefieldmba
Twitter: @BobLovesData

From: Naganarasimha G R (Naga) 
Sent: Wednesday, November 04, 2015 4:26 PM
To: user@hadoop.apache.org 
Subject: RE: hadoop not using whole disk for HDFS

Better would be to stop the daemons and copy the data from /hadoop/hdfs/data to /home/hdfs/data
, reconfigure dfs.datanode.data.dir to /home/hdfs/data and then start the daemons. If the
data is comparitively less !

Ensure you have the backup if have any critical data !



Regards,

+ Naga


--------------------------------------------------------------------------------

From: Adaryl "Bob" Wakefield, MBA [adaryl.wakefield@hotmail.com]
Sent: Thursday, November 05, 2015 03:40
To: user@hadoop.apache.org
Subject: Re: hadoop not using whole disk for HDFS


So like I can just create a new folder in the home directory like:
home/hdfs/data
and then set dfs.datanode.data.dir to:
/hadoop/hdfs/data,home/hdfs/data

Restart the node and that should do it correct?

Adaryl "Bob" Wakefield, MBA
Principal
Mass Street Analytics, LLC
913.938.6685
www.linkedin.com/in/bobwakefieldmba
Twitter: @BobLovesData

From: Naganarasimha G R (Naga) 
Sent: Wednesday, November 04, 2015 3:59 PM
To: user@hadoop.apache.org 
Subject: RE: hadoop not using whole disk for HDFS

Hi Bob,



Seems like you have configured to disk dir to be other than an folder in /home, if so try
creating another folder and add to "dfs.datanode.data.dir" seperated by comma instead of trying
to reset the default.

And its also advised not to use the root partition "/" to be configured for HDFS data dir,
if the Dir usage hits the maximum then OS might fail to function properly.



Regards,

+ Naga


--------------------------------------------------------------------------------

From: P lva [ruvikal@gmail.com]
Sent: Thursday, November 05, 2015 03:11
To: user@hadoop.apache.org
Subject: Re: hadoop not using whole disk for HDFS


What does your dfs.datanode.data.dir point to ?



On Wed, Nov 4, 2015 at 4:14 PM, Adaryl "Bob" Wakefield, MBA <adaryl.wakefield@hotmail.com>
wrote:

        Filesystem Size Used Avail Use% Mounted on 
        /dev/mapper/centos-root 50G 12G 39G 23% / 
        devtmpfs 16G 0 16G 0% /dev 
        tmpfs 16G 0 16G 0% /dev/shm 
        tmpfs 16G 1.4G 15G 9% /run 
        tmpfs 16G 0 16G 0% /sys/fs/cgroup 
        /dev/sda2 494M 123M 372M 25% /boot 
        /dev/mapper/centos-home 2.7T 33M 2.7T 1% /home 


  That’s from one datanode. The second one is nearly identical. I discovered that 50GB is
actually a default. That seems really weird. Disk space is cheap. Why would you not just use
most of the disk and why is it so hard to reset the default?

  Adaryl "Bob" Wakefield, MBA
  Principal
  Mass Street Analytics, LLC
  913.938.6685
  www.linkedin.com/in/bobwakefieldmba
  Twitter: @BobLovesData

  From: Chris Nauroth 
  Sent: Wednesday, November 04, 2015 12:16 PM
  To: user@hadoop.apache.org 
  Subject: Re: hadoop not using whole disk for HDFS

  How are those drives partitioned?  Is it possible that the directories pointed to by the
dfs.datanode.data.dir property in hdfs-site.xml reside on partitions that are sized to only
100 GB?  Running commands like df would be a good way to check this at the OS level, independently
of Hadoop.

  --Chris Nauroth

  From: MBA <adaryl.wakefield@hotmail.com>
  Reply-To: "user@hadoop.apache.org" <user@hadoop.apache.org>
  Date: Tuesday, November 3, 2015 at 11:16 AM
  To: "user@hadoop.apache.org" <user@hadoop.apache.org>
  Subject: Re: hadoop not using whole disk for HDFS


  Yeah. It has the current value of 1073741824 which is like 1.07 gig.

  B.
  From: Chris Nauroth 
  Sent: Tuesday, November 03, 2015 11:57 AM
  To: user@hadoop.apache.org 
  Subject: Re: hadoop not using whole disk for HDFS

  Hi Bob,

  Does the hdfs-site.xml configuration file contain the property dfs.datanode.du.reserved?
 If this is defined, then the DataNode intentionally will not use this space for storage of
replicas.

  <property>
    <name>dfs.datanode.du.reserved</name>
    <value>0</value>
    <description>Reserved space in bytes per volume. Always leave this much space free
for non dfs use.
    </description>
  </property>

  --Chris Nauroth

  From: MBA <adaryl.wakefield@hotmail.com>
  Reply-To: "user@hadoop.apache.org" <user@hadoop.apache.org>
  Date: Tuesday, November 3, 2015 at 10:51 AM
  To: "user@hadoop.apache.org" <user@hadoop.apache.org>
  Subject: hadoop not using whole disk for HDFS


  I’ve got the Hortonworks distro running on a three node cluster. For some reason the disk
available for HDFS is MUCH less than the total disk space. Both of my data nodes have 3TB
hard drives. Only 100GB of that is being used for HDFS. Is it possible that I have a setting
wrong somewhere? 
  B.

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