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Posted to user@hadoop.apache.org by Kondala Palaka <kp...@gurudatasolutions.com> on 2015/01/13 23:46:23 UTC
Namenode HA and data loss
Hi friends,
Is there really zero data loss in case of a namenode failure in an HA
(active-passive) environment?
Thanks in advance for any pointers..
Kondala Palaka
Re: Namenode HA and data loss
Posted by Chris Nauroth <cn...@hortonworks.com>.
Yes, if this is an HDFS cluster deployed with HA using the Quorum Journal
Manager, then it is protected against data loss. This documentation page
describes the configuration and how the architecture achieves it.
http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/HDFSHighAvailabilityWithQJM.html
There can be a small risk of an HDFS client reading stale data from an old
NameNode that still thinks it's active. To mitigate against this, you can
configure fencing methods to stop the old NameNode. For more information
on this, see "dfs.ha.fencing.methods" in the same document.
Chris Nauroth
Hortonworks
http://hortonworks.com/
On Tue, Jan 13, 2015 at 2:46 PM, Kondala Palaka <
kpalaka@gurudatasolutions.com> wrote:
> Hi friends,
>
>
>
> Is there really *zero* data loss in case of a namenode failure in an HA
> (active-passive) environment?
>
>
>
> Thanks in advance for any pointers..
>
> *Kondala Palaka*
>
>
>
--
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any printing, copying, dissemination, distribution, disclosure or
forwarding of this communication is strictly prohibited. If you have
received this communication in error, please contact the sender immediately
and delete it from your system. Thank You.
Re: Namenode HA and data loss
Posted by Chris Nauroth <cn...@hortonworks.com>.
Yes, if this is an HDFS cluster deployed with HA using the Quorum Journal
Manager, then it is protected against data loss. This documentation page
describes the configuration and how the architecture achieves it.
http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/HDFSHighAvailabilityWithQJM.html
There can be a small risk of an HDFS client reading stale data from an old
NameNode that still thinks it's active. To mitigate against this, you can
configure fencing methods to stop the old NameNode. For more information
on this, see "dfs.ha.fencing.methods" in the same document.
Chris Nauroth
Hortonworks
http://hortonworks.com/
On Tue, Jan 13, 2015 at 2:46 PM, Kondala Palaka <
kpalaka@gurudatasolutions.com> wrote:
> Hi friends,
>
>
>
> Is there really *zero* data loss in case of a namenode failure in an HA
> (active-passive) environment?
>
>
>
> Thanks in advance for any pointers..
>
> *Kondala Palaka*
>
>
>
--
CONFIDENTIALITY NOTICE
NOTICE: This message is intended for the use of the individual or entity to
which it is addressed and may contain information that is confidential,
privileged and exempt from disclosure under applicable law. If the reader
of this message is not the intended recipient, you are hereby notified that
any printing, copying, dissemination, distribution, disclosure or
forwarding of this communication is strictly prohibited. If you have
received this communication in error, please contact the sender immediately
and delete it from your system. Thank You.
Re: Namenode HA and data loss
Posted by Chris Nauroth <cn...@hortonworks.com>.
Yes, if this is an HDFS cluster deployed with HA using the Quorum Journal
Manager, then it is protected against data loss. This documentation page
describes the configuration and how the architecture achieves it.
http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/HDFSHighAvailabilityWithQJM.html
There can be a small risk of an HDFS client reading stale data from an old
NameNode that still thinks it's active. To mitigate against this, you can
configure fencing methods to stop the old NameNode. For more information
on this, see "dfs.ha.fencing.methods" in the same document.
Chris Nauroth
Hortonworks
http://hortonworks.com/
On Tue, Jan 13, 2015 at 2:46 PM, Kondala Palaka <
kpalaka@gurudatasolutions.com> wrote:
> Hi friends,
>
>
>
> Is there really *zero* data loss in case of a namenode failure in an HA
> (active-passive) environment?
>
>
>
> Thanks in advance for any pointers..
>
> *Kondala Palaka*
>
>
>
--
CONFIDENTIALITY NOTICE
NOTICE: This message is intended for the use of the individual or entity to
which it is addressed and may contain information that is confidential,
privileged and exempt from disclosure under applicable law. If the reader
of this message is not the intended recipient, you are hereby notified that
any printing, copying, dissemination, distribution, disclosure or
forwarding of this communication is strictly prohibited. If you have
received this communication in error, please contact the sender immediately
and delete it from your system. Thank You.
Re: Namenode HA and data loss
Posted by Chris Nauroth <cn...@hortonworks.com>.
Yes, if this is an HDFS cluster deployed with HA using the Quorum Journal
Manager, then it is protected against data loss. This documentation page
describes the configuration and how the architecture achieves it.
http://hadoop.apache.org/docs/r2.6.0/hadoop-project-dist/hadoop-hdfs/HDFSHighAvailabilityWithQJM.html
There can be a small risk of an HDFS client reading stale data from an old
NameNode that still thinks it's active. To mitigate against this, you can
configure fencing methods to stop the old NameNode. For more information
on this, see "dfs.ha.fencing.methods" in the same document.
Chris Nauroth
Hortonworks
http://hortonworks.com/
On Tue, Jan 13, 2015 at 2:46 PM, Kondala Palaka <
kpalaka@gurudatasolutions.com> wrote:
> Hi friends,
>
>
>
> Is there really *zero* data loss in case of a namenode failure in an HA
> (active-passive) environment?
>
>
>
> Thanks in advance for any pointers..
>
> *Kondala Palaka*
>
>
>
--
CONFIDENTIALITY NOTICE
NOTICE: This message is intended for the use of the individual or entity to
which it is addressed and may contain information that is confidential,
privileged and exempt from disclosure under applicable law. If the reader
of this message is not the intended recipient, you are hereby notified that
any printing, copying, dissemination, distribution, disclosure or
forwarding of this communication is strictly prohibited. If you have
received this communication in error, please contact the sender immediately
and delete it from your system. Thank You.