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Date: Thu, 27 Feb 2014 11:08:49 +0100
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 <CAO6W-2eChLbabLRvs13OYXBZqoES1VDb1miBjR2CJajBtzq4VA@mail.gmail.com>
Subject: Re: Question about DataNode
From: Bertrand Dechoux <dechouxb@gmail.com>
To: "user@hadoop.apache.org" <user@hadoop.apache.org>
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I am not sure what your question is. You might want to be more explicit and
read more about Hadoop architecture and the roles of the various daemons. A
directory is only metadata so you can mess around with DataNodes if you
want but they are not involved.

Regards

Bertrand


Bertrand Dechoux


On Thu, Feb 27, 2014 at 10:12 AM, Juan Carlos <jucaf1@gmail.com> wrote:

> Hi Edward,
> maybe you are sending your request to the master from the slave. I don't
> are sure, but I think that secondary never answer any request, neither read
> request, and you have to modify your config files by hand to change your
> slave to be master.
>
> I haven't tested so much with master/slave configurations, I only tested
> with QJM and NFS syncronizations, in these cases whenever you start
> namenodes they first get syncronized before being able to promote to active
> namenode by checking journalnodes or NFS looking for changes in metadata to
> update them.
>
>
> 2014-02-27 9:52 GMT+01:00 EdwardKing <zhangsc@neusoft.com>:
>
>  Two node,one is master,another is slave, I kill DataNode under slave,
>> then create directory by dfs command under master machine:
>> [hadoop@master]$./start-all.sh
>>  [hadoop@slave]$ jps
>> 9917 DataNode
>> 10152 Jps
>> [hadoop@slave]$ kill -9 9917
>> [hadoop@master]$ hadoop dfs -mkdir test
>> [hadoop@master]$ hadoop dfs -ls
>> drwxr-xr-x   - hadoop supergroup          0 2014-02-27 00:15 test
>> I guess test directory can't exist under slave,because slave is killed.
>> Right?
>> Then I restart service under master,like follows:
>>  [hadoop@master]$./start-all.sh
>>
>> This time I find slave also contains test directory, why? Is hadoop2.2.0
>> can automatic recovery?
>> Any idea will be appreciated.
>> Best regards,
>> Edward
>>
>>
>>
>>
>>
>> ---------------------------------------------------------------------------------------------------
>> Confidentiality Notice: The information contained in this e-mail and any
>> accompanying attachment(s)
>> is intended only for the use of the intended recipient and may be
>> confidential and/or privileged of
>> Neusoft Corporation, its subsidiaries and/or its affiliates. If any
>> reader of this communication is
>> not the intended recipient, unauthorized use, forwarding, printing,
>> storing, disclosure or copying
>> is strictly prohibited, and may be unlawful.If you have received this
>> communication in error,please
>> immediately notify the sender by return e-mail, and delete the original
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>>
>> ---------------------------------------------------------------------------------------------------
>>
>
>

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Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">I am not sure what your question is. You might want to be =
more explicit and read more about Hadoop architecture and the roles of the =
various daemons. A directory is only metadata so you can mess around with D=
ataNodes if you want but they are not involved.<div>
<br></div><div>Regards</div><div><br></div><div>Bertrand</div><div><br></di=
v></div><div class=3D"gmail_extra"><br clear=3D"all"><div>Bertrand Dechoux<=
/div>
<br><br><div class=3D"gmail_quote">On Thu, Feb 27, 2014 at 10:12 AM, Juan C=
arlos <span dir=3D"ltr">&lt;<a href=3D"mailto:jucaf1@gmail.com" target=3D"_=
blank">jucaf1@gmail.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail=
_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:=
1ex">
<div dir=3D"ltr"><div><div><div>Hi Edward,<br></div>maybe you are sending y=
our request to the master from the slave. I don&#39;t are sure, but I think=
 that secondary never answer any request, neither read request, and you hav=
e to modify your config files by hand  to change your slave to be master.<b=
r>

<br></div>I haven&#39;t tested so much with master/slave configurations, I =
only tested with QJM and NFS syncronizations, in these cases whenever you s=
tart namenodes they first get syncronized before being able to promote to a=
ctive namenode by checking journalnodes or NFS looking for changes in metad=
ata to update them.<br>

</div></div><div class=3D"gmail_extra"><br><br><div class=3D"gmail_quote">2=
014-02-27 9:52 GMT+01:00 EdwardKing <span dir=3D"ltr">&lt;<a href=3D"mailto=
:zhangsc@neusoft.com" target=3D"_blank">zhangsc@neusoft.com</a>&gt;</span>:=
<div>
<div class=3D"h5"><br><blockquote class=3D"gmail_quote" style=3D"margin:0 0=
 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<u></u>


<div bgcolor=3D"#ffffff">
<div><font face=3D"Arial">Two node,one is master,another is slave,=A0I=20
kill DataNode under slave, then create directory by dfs command under maste=
r=20
machine:</font></div>
<div><font face=3D"Arial">[hadoop@master]$./start-all.sh</font></div>
<div><font face=3D"Arial">
<div>[hadoop@slave]$ jps<br>9917 DataNode<br>10152 Jps</div>
<div>[hadoop@slave]$ kill -9 9917</div>
<div></div></font><font face=3D"Arial">[hadoop@master]$ hadoop dfs -mkdir=
=20
test</font></div></div>
<div><font face=3D"Arial">[hadoop@master]$ hadoop dfs -ls=20
<br>drwxr-xr-x=A0=A0 - hadoop=20
supergroup=A0=A0=A0=A0=A0=A0=A0=A0=A0 0 2014-02-27=20
00:15 test<br></font></div>
<div><font face=3D"Arial">I guess test directory can&#39;t exist under=20
slave,because slave is killed. Right?</font></div>
<div><font face=3D"Arial">Then I restart service under master,like=20
follows:</font></div>
<div><font face=3D"Arial">
<div><font face=3D"Arial">[hadoop@master]$./start-all.sh</font></div>
<div>=A0</div>
<div>This time I find slave also contains test directory, why? Is hadoop2.2=
.0=20
can automatic recovery? </div>
<div>Any idea will be appreciated.</div>
<div>Best regards,</div>
<div>Edward</div>
<div>=A0</div>
<div>=A0</div>
<div>=A0</div></font></div><p>---------------------------------------------=
------------------------------------------------------<br>
Confidentiality Notice: The information contained in this e-mail and any ac=
companying attachment(s) <br>
is intended only for the use of the intended recipient and may be confident=
ial and/or privileged of <br>
Neusoft Corporation, its subsidiaries and/or its affiliates. If any reader =
of this communication is <br>
not the intended recipient, unauthorized use, forwarding, printing,=A0 stor=
ing, disclosure or copying <br>
is strictly prohibited, and may be unlawful.If you have received this commu=
nication in error,please <br>
immediately notify the sender by return e-mail, and delete the original mes=
sage and all copies from <br>
your system. Thank you. <br>
---------------------------------------------------------------------------=
------------------------</p>
</blockquote></div></div></div><br></div>
</blockquote></div><br></div>

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