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Posted to hdfs-user@hadoop.apache.org by Rahul Bhattacharjee <ra...@gmail.com> on 2013/05/17 19:10:45 UTC
HDFS write failures!
Hi,
I was going through some documents about HDFS write pattern. It looks like
the write pipeline is closed when a error is encountered and the faulty
node is taken out of the pipeline and the write continues.Few other
intermediate steps are to move the un-acked packets from ack queue to the
data queue.
My question is , is this faulty data node is reported to the NN and whether
NN would continue to use it as a valid DN while serving other write
requests in future or will it make it as faulty ?
Thanks,
Rahul
Re: HDFS write failures!
Posted by Rahul Bhattacharjee <ra...@gmail.com>.
Thanks Ravi for the pointer. I will look into the pointed out source.
Rahul
On Fri, May 17, 2013 at 11:44 PM, Ravi Prakash <ra...@ymail.com> wrote:
> Hi,
>
> I couldn't find any code that would relay this failure to the NN. The
> relevant code is in DFSOutputStream:DataStreamer:processDatanodeError()
>
> For trunk:
> https://svn.apache.org/repos/asf/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
> For 0.20:
> http://javasourcecode.org/html/open-source/hadoop/hadoop-0.20.203.0/org/apache/hadoop/hdfs/DFSClient.DFSOutputStream.java.html
>
> I believe the assumption here is that the NN should independently discover
> the failed node. Also, some failures might not be worthy of being reported
> because the DN is expected to recover from them.
>
> Ravi.
>
>
> ------------------------------
> *From:* Rahul Bhattacharjee <ra...@gmail.com>
> *To:* "user@hadoop.apache.org" <us...@hadoop.apache.org>
> *Sent:* Friday, May 17, 2013 12:10 PM
> *Subject:* HDFS write failures!
>
> Hi,
>
> I was going through some documents about HDFS write pattern. It looks like
> the write pipeline is closed when a error is encountered and the faulty
> node is taken out of the pipeline and the write continues.Few other
> intermediate steps are to move the un-acked packets from ack queue to the
> data queue.
>
> My question is , is this faulty data node is reported to the NN and
> whether NN would continue to use it as a valid DN while serving other write
> requests in future or will it make it as faulty ?
>
> Thanks,
> Rahul
>
>
>
Re: HDFS write failures!
Posted by Rahul Bhattacharjee <ra...@gmail.com>.
Thanks Ravi for the pointer. I will look into the pointed out source.
Rahul
On Fri, May 17, 2013 at 11:44 PM, Ravi Prakash <ra...@ymail.com> wrote:
> Hi,
>
> I couldn't find any code that would relay this failure to the NN. The
> relevant code is in DFSOutputStream:DataStreamer:processDatanodeError()
>
> For trunk:
> https://svn.apache.org/repos/asf/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
> For 0.20:
> http://javasourcecode.org/html/open-source/hadoop/hadoop-0.20.203.0/org/apache/hadoop/hdfs/DFSClient.DFSOutputStream.java.html
>
> I believe the assumption here is that the NN should independently discover
> the failed node. Also, some failures might not be worthy of being reported
> because the DN is expected to recover from them.
>
> Ravi.
>
>
> ------------------------------
> *From:* Rahul Bhattacharjee <ra...@gmail.com>
> *To:* "user@hadoop.apache.org" <us...@hadoop.apache.org>
> *Sent:* Friday, May 17, 2013 12:10 PM
> *Subject:* HDFS write failures!
>
> Hi,
>
> I was going through some documents about HDFS write pattern. It looks like
> the write pipeline is closed when a error is encountered and the faulty
> node is taken out of the pipeline and the write continues.Few other
> intermediate steps are to move the un-acked packets from ack queue to the
> data queue.
>
> My question is , is this faulty data node is reported to the NN and
> whether NN would continue to use it as a valid DN while serving other write
> requests in future or will it make it as faulty ?
>
> Thanks,
> Rahul
>
>
>
Re: HDFS write failures!
Posted by Rahul Bhattacharjee <ra...@gmail.com>.
Thanks Ravi for the pointer. I will look into the pointed out source.
Rahul
On Fri, May 17, 2013 at 11:44 PM, Ravi Prakash <ra...@ymail.com> wrote:
> Hi,
>
> I couldn't find any code that would relay this failure to the NN. The
> relevant code is in DFSOutputStream:DataStreamer:processDatanodeError()
>
> For trunk:
> https://svn.apache.org/repos/asf/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
> For 0.20:
> http://javasourcecode.org/html/open-source/hadoop/hadoop-0.20.203.0/org/apache/hadoop/hdfs/DFSClient.DFSOutputStream.java.html
>
> I believe the assumption here is that the NN should independently discover
> the failed node. Also, some failures might not be worthy of being reported
> because the DN is expected to recover from them.
>
> Ravi.
>
>
> ------------------------------
> *From:* Rahul Bhattacharjee <ra...@gmail.com>
> *To:* "user@hadoop.apache.org" <us...@hadoop.apache.org>
> *Sent:* Friday, May 17, 2013 12:10 PM
> *Subject:* HDFS write failures!
>
> Hi,
>
> I was going through some documents about HDFS write pattern. It looks like
> the write pipeline is closed when a error is encountered and the faulty
> node is taken out of the pipeline and the write continues.Few other
> intermediate steps are to move the un-acked packets from ack queue to the
> data queue.
>
> My question is , is this faulty data node is reported to the NN and
> whether NN would continue to use it as a valid DN while serving other write
> requests in future or will it make it as faulty ?
>
> Thanks,
> Rahul
>
>
>
Re: HDFS write failures!
Posted by Rahul Bhattacharjee <ra...@gmail.com>.
Thanks Ravi for the pointer. I will look into the pointed out source.
Rahul
On Fri, May 17, 2013 at 11:44 PM, Ravi Prakash <ra...@ymail.com> wrote:
> Hi,
>
> I couldn't find any code that would relay this failure to the NN. The
> relevant code is in DFSOutputStream:DataStreamer:processDatanodeError()
>
> For trunk:
> https://svn.apache.org/repos/asf/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
> For 0.20:
> http://javasourcecode.org/html/open-source/hadoop/hadoop-0.20.203.0/org/apache/hadoop/hdfs/DFSClient.DFSOutputStream.java.html
>
> I believe the assumption here is that the NN should independently discover
> the failed node. Also, some failures might not be worthy of being reported
> because the DN is expected to recover from them.
>
> Ravi.
>
>
> ------------------------------
> *From:* Rahul Bhattacharjee <ra...@gmail.com>
> *To:* "user@hadoop.apache.org" <us...@hadoop.apache.org>
> *Sent:* Friday, May 17, 2013 12:10 PM
> *Subject:* HDFS write failures!
>
> Hi,
>
> I was going through some documents about HDFS write pattern. It looks like
> the write pipeline is closed when a error is encountered and the faulty
> node is taken out of the pipeline and the write continues.Few other
> intermediate steps are to move the un-acked packets from ack queue to the
> data queue.
>
> My question is , is this faulty data node is reported to the NN and
> whether NN would continue to use it as a valid DN while serving other write
> requests in future or will it make it as faulty ?
>
> Thanks,
> Rahul
>
>
>
Re: HDFS write failures!
Posted by Ravi Prakash <ra...@ymail.com>.
Hi,
I couldn't find any code that would relay this failure to the NN. The relevant code is in DFSOutputStream:DataStreamer:processDatanodeError()
For trunk: https://svn.apache.org/repos/asf/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
For 0.20: http://javasourcecode.org/html/open-source/hadoop/hadoop-0.20.203.0/org/apache/hadoop/hdfs/DFSClient.DFSOutputStream.java.html
I believe the assumption here is that the NN should independently discover the failed node. Also, some failures might not be worthy of being reported because the DN is expected to recover from them.
Ravi.
________________________________
From: Rahul Bhattacharjee <ra...@gmail.com>
To: "user@hadoop.apache.org" <us...@hadoop.apache.org>
Sent: Friday, May 17, 2013 12:10 PM
Subject: HDFS write failures!
Hi,
I was going through some documents about HDFS write pattern. It looks like the write pipeline is closed when a error is encountered and the faulty node is taken out of the pipeline and the write continues.Few other intermediate steps are to move the un-acked packets from ack queue to the data queue.
My question is , is this faulty data node is reported to the NN and whether NN would continue to use it as a valid DN while serving other write requests in future or will it make it as faulty ?
Thanks,
Rahul
Re: HDFS write failures!
Posted by Ravi Prakash <ra...@ymail.com>.
Hi,
I couldn't find any code that would relay this failure to the NN. The relevant code is in DFSOutputStream:DataStreamer:processDatanodeError()
For trunk: https://svn.apache.org/repos/asf/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
For 0.20: http://javasourcecode.org/html/open-source/hadoop/hadoop-0.20.203.0/org/apache/hadoop/hdfs/DFSClient.DFSOutputStream.java.html
I believe the assumption here is that the NN should independently discover the failed node. Also, some failures might not be worthy of being reported because the DN is expected to recover from them.
Ravi.
________________________________
From: Rahul Bhattacharjee <ra...@gmail.com>
To: "user@hadoop.apache.org" <us...@hadoop.apache.org>
Sent: Friday, May 17, 2013 12:10 PM
Subject: HDFS write failures!
Hi,
I was going through some documents about HDFS write pattern. It looks like the write pipeline is closed when a error is encountered and the faulty node is taken out of the pipeline and the write continues.Few other intermediate steps are to move the un-acked packets from ack queue to the data queue.
My question is , is this faulty data node is reported to the NN and whether NN would continue to use it as a valid DN while serving other write requests in future or will it make it as faulty ?
Thanks,
Rahul
Re: HDFS write failures!
Posted by Ravi Prakash <ra...@ymail.com>.
Hi,
I couldn't find any code that would relay this failure to the NN. The relevant code is in DFSOutputStream:DataStreamer:processDatanodeError()
For trunk: https://svn.apache.org/repos/asf/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
For 0.20: http://javasourcecode.org/html/open-source/hadoop/hadoop-0.20.203.0/org/apache/hadoop/hdfs/DFSClient.DFSOutputStream.java.html
I believe the assumption here is that the NN should independently discover the failed node. Also, some failures might not be worthy of being reported because the DN is expected to recover from them.
Ravi.
________________________________
From: Rahul Bhattacharjee <ra...@gmail.com>
To: "user@hadoop.apache.org" <us...@hadoop.apache.org>
Sent: Friday, May 17, 2013 12:10 PM
Subject: HDFS write failures!
Hi,
I was going through some documents about HDFS write pattern. It looks like the write pipeline is closed when a error is encountered and the faulty node is taken out of the pipeline and the write continues.Few other intermediate steps are to move the un-acked packets from ack queue to the data queue.
My question is , is this faulty data node is reported to the NN and whether NN would continue to use it as a valid DN while serving other write requests in future or will it make it as faulty ?
Thanks,
Rahul
Re: HDFS write failures!
Posted by Ravi Prakash <ra...@ymail.com>.
Hi,
I couldn't find any code that would relay this failure to the NN. The relevant code is in DFSOutputStream:DataStreamer:processDatanodeError()
For trunk: https://svn.apache.org/repos/asf/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
For 0.20: http://javasourcecode.org/html/open-source/hadoop/hadoop-0.20.203.0/org/apache/hadoop/hdfs/DFSClient.DFSOutputStream.java.html
I believe the assumption here is that the NN should independently discover the failed node. Also, some failures might not be worthy of being reported because the DN is expected to recover from them.
Ravi.
________________________________
From: Rahul Bhattacharjee <ra...@gmail.com>
To: "user@hadoop.apache.org" <us...@hadoop.apache.org>
Sent: Friday, May 17, 2013 12:10 PM
Subject: HDFS write failures!
Hi,
I was going through some documents about HDFS write pattern. It looks like the write pipeline is closed when a error is encountered and the faulty node is taken out of the pipeline and the write continues.Few other intermediate steps are to move the un-acked packets from ack queue to the data queue.
My question is , is this faulty data node is reported to the NN and whether NN would continue to use it as a valid DN while serving other write requests in future or will it make it as faulty ?
Thanks,
Rahul