Re: Hodoop namenode startup problem

2010-08-05 Thread edward choi
I've fixed the problem.

The reason namenode won't start was that I accidentally started the cluster
with root account.
This somehow changed the ownership of some hadoop-related files(ex: log
files, and hadoop.tmp.dir/dfs/name/current/edits) from hadoop:hadoop to
root:root.
After I fixed the ownership issue, everything went fine.
Thanks for the concern.

2010/8/5 Harsh J qwertyman...@gmail.com

 Could you check the NameNode/SecondaryNameNode logs and try to find
 the exact issue? Post the errors (if) it contains here, so we can try
 to help you better.

 On Thu, Aug 5, 2010 at 9:39 AM, edward choi mp2...@gmail.com wrote:
  I am currently stuck with hadoop namenode that won't start.
 
  When I type start-all.sh, everything prints out fine.
  But when I type jps, only JobTracker is activated.
 
  When this happens, I usually format the namenode.
 
  But the problem is that there are 500gigs of date in HDFS.
  So I really want to save the data.
 
  Can anyone give help please?
 



 --
 Harsh J
 www.harshj.com



hdfs space problem.

2010-08-05 Thread Raj V


I run a 512 node hadoop cluster. Yesterday I moved 30Gb of compressed data from 
a NFS mounted partition by running  on the namenode

hadoop fs -copyFromLocal  /mnt/data/data1 /mnt/data/data2 mnt/data/data3 
hdfs:/data

When the job completed the local disk on the namenode was 40% full ( Most of it 
used by the dfs dierctories) while the others had 1% disk utilization.

Just to see if there was an issue, I deleted the hdfs:/data directory and 
restarted the move from a datanode. 

Once again the disk space on that data node was substantially over utilized.

I would have assumed that the disk space would be more or less uniformly 
consumed on all the data nodes.

Is there a reason why one disk would be over utilized? 

Do I have to run balancer everytime I copy data?

Am I missing something?

Raj

centralized record reader in new API

2010-08-05 Thread Gang Luo
Hi all,
to create a RecordReader in new API, we needs a TaskAttemptContext object, 
which 
seems to me the RecordReader should only be created on each split that has been 
assigned a task ID. However, I want to do a centralized sampling and create 
record reader on some splits before the job is submitted. What I am doing is 
create a dummy TaskAttemptContext and use it to create record reader, but not 
sure whether there is some side-effects. Is there any better way to do this? 
Why 
we are not supposed to create record reader centrally as indicated by the new 
API?

Thanks,
-Gang






RE: hdfs space problem.

2010-08-05 Thread Dmitry Pushkarev
when you copy files and have a local datanode - first copy will end up
there.
Just stop datanode at the node from which you copy files, and they will end
up on random nodes.

Also don't run datanode at the same machine as namenode.

-Original Message-
From: Raj V [mailto:rajv...@yahoo.com] 
Sent: Thursday, August 05, 2010 8:33 AM
To: common-user@hadoop.apache.org
Subject: hdfs space problem.



I run a 512 node hadoop cluster. Yesterday I moved 30Gb of compressed data
from 
a NFS mounted partition by running  on the namenode

hadoop fs -copyFromLocal  /mnt/data/data1 /mnt/data/data2 mnt/data/data3 
hdfs:/data

When the job completed the local disk on the namenode was 40% full ( Most of
it 
used by the dfs dierctories) while the others had 1% disk utilization.

Just to see if there was an issue, I deleted the hdfs:/data directory and 
restarted the move from a datanode. 

Once again the disk space on that data node was substantially over utilized.

I would have assumed that the disk space would be more or less uniformly 
consumed on all the data nodes.

Is there a reason why one disk would be over utilized? 

Do I have to run balancer everytime I copy data?

Am I missing something?

Raj



Problems running hadoop on Amazon Elastic MapReduce

2010-08-05 Thread grabbler

I am a complete newbie to hadoop.  I'm running a job on 19 Amazon Elastic
MapReduce servers and am trying to understand two separate issues.   

1) The job is ending with an error  ERROR
org.apache.pig.tools.grunt.GruntParser - ERROR 6015: During execution,
encountered a Hadoop error. I do not have the hadoop log files and will
have to rerun the job with different settings to obtain them.  Once I have
them, I'll add them to the posting.
2) The job seems to complete %19 within 1 minute and then takes 15 minutes
to complete another %20.  It then takes over 40 minutes to complete the last
%60.  Why the sudden slow down?  Am I misunderstanding the messages?

The following is the ouput from the job:

10/08/05 16:39:30 WARN conf.Configuration: DEPRECATED: hadoop-site.xml found
in the classpath. Usage of hadoop-site.xml is deprecated. Instead use
core-site.xml, mapred-site.xml and hdfs-site.xml to override properties of
core-default.xml, mapred-default.xml and hdfs-default.xml respectively
2010-08-05 16:39:30,688 [main] INFO  org.apache.pig.Main - Logging error
messages to: /mnt/var/lib/hadoop/steps/2/pig_1281026370670.log
2010-08-05 16:39:31,663 [main] INFO 
org.apache.hadoop.fs.s3native.NativeS3FileSystem - Opening
'/scripts/calculateTrackingErrors.pig' for reading
2010-08-05 16:39:32,071 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.HExecutionEngine - Connecting
to hadoop file system at:
hdfs://domU-12-31-39-09-F1-D2.compute-1.internal:9000
2010-08-05 16:39:32,662 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.HExecutionEngine - Connecting
to map-reduce job tracker at: domU-12-31-39-09-F1-D2.compute-1.internal:9001
2010-08-05 16:39:33,360 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No column pruned
for covMatrix
2010-08-05 16:39:33,360 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No map keys pruned
for covMatrix
2010-08-05 16:39:33,362 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No column pruned
for fundExposures2
2010-08-05 16:39:33,362 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No map keys pruned
for fundExposures2
2010-08-05 16:39:33,363 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No column pruned
for fundExposures1
2010-08-05 16:39:33,363 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No map keys pruned
for fundExposures1
2010-08-05 16:39:33,469 [main] WARN 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- Encountered Warning DID_NOT_FIND_LOAD_ONLY_MAP_PLAN 1 time(s).
2010-08-05 16:39:33,484 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MRCompiler$LastInputStreamingOptimizer
- Rewrite: POPackage-POForEach to POJoinPackage
2010-08-05 16:39:33,485 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MRCompiler$LastInputStreamingOptimizer
- Rewrite: POPackage-POForEach to POJoinPackage
2010-08-05 16:39:33,486 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MRCompiler$LastInputStreamingOptimizer
- Rewrite: POPackage-POForEach to POJoinPackage
2010-08-05 16:39:33,495 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MultiQueryOptimizer
- MR plan size before optimization: 5
2010-08-05 16:39:33,496 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MultiQueryOptimizer
- Merged 0 out of total 3 MR operators.
2010-08-05 16:39:33,496 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MultiQueryOptimizer
- MR plan size after optimization: 5
2010-08-05 16:39:33,501 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.AccumulatorOptimizer
- Reducer is to run in accumulative mode.
2010-08-05 16:39:33,502 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.AccumulatorOptimizer
- Reducer is to run in accumulative mode.
2010-08-05 16:39:34,465 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler
- Setting up single store job
2010-08-05 16:39:34,559 [Thread-12] WARN  org.apache.hadoop.mapred.JobClient
- Use GenericOptionsParser for parsing the arguments. Applications should
implement Tool for the same.
2010-08-05 16:39:35,585 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- Cannot get jobid for this job
2010-08-05 16:39:42,847 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- 0% complete
2010-08-05 16:39:55,415 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- 5% complete
2010-08-05 16:39:56,464 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- 10% complete
2010-08-05 16:40:08,548 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- 11% complete
2010-08-05 16:40:11,561 

RE: Problems running hadoop on Amazon Elastic MapReduce

2010-08-05 Thread Ankit Bhatnagar
Hi,
EMR has a live debug option in the panel, you will find the logs there as well.


Ankit

-Original Message-
From: grabbler [mailto:twiza...@gmail.com] 
Sent: Thursday, August 05, 2010 2:37 PM
To: core-u...@hadoop.apache.org
Subject: Problems running hadoop on Amazon Elastic MapReduce


I am a complete newbie to hadoop.  I'm running a job on 19 Amazon Elastic
MapReduce servers and am trying to understand two separate issues.   

1) The job is ending with an error  ERROR
org.apache.pig.tools.grunt.GruntParser - ERROR 6015: During execution,
encountered a Hadoop error. I do not have the hadoop log files and will
have to rerun the job with different settings to obtain them.  Once I have
them, I'll add them to the posting.
2) The job seems to complete %19 within 1 minute and then takes 15 minutes
to complete another %20.  It then takes over 40 minutes to complete the last
%60.  Why the sudden slow down?  Am I misunderstanding the messages?

The following is the ouput from the job:

10/08/05 16:39:30 WARN conf.Configuration: DEPRECATED: hadoop-site.xml found
in the classpath. Usage of hadoop-site.xml is deprecated. Instead use
core-site.xml, mapred-site.xml and hdfs-site.xml to override properties of
core-default.xml, mapred-default.xml and hdfs-default.xml respectively
2010-08-05 16:39:30,688 [main] INFO  org.apache.pig.Main - Logging error
messages to: /mnt/var/lib/hadoop/steps/2/pig_1281026370670.log
2010-08-05 16:39:31,663 [main] INFO 
org.apache.hadoop.fs.s3native.NativeS3FileSystem - Opening
'/scripts/calculateTrackingErrors.pig' for reading
2010-08-05 16:39:32,071 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.HExecutionEngine - Connecting
to hadoop file system at:
hdfs://domU-12-31-39-09-F1-D2.compute-1.internal:9000
2010-08-05 16:39:32,662 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.HExecutionEngine - Connecting
to map-reduce job tracker at: domU-12-31-39-09-F1-D2.compute-1.internal:9001
2010-08-05 16:39:33,360 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No column pruned
for covMatrix
2010-08-05 16:39:33,360 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No map keys pruned
for covMatrix
2010-08-05 16:39:33,362 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No column pruned
for fundExposures2
2010-08-05 16:39:33,362 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No map keys pruned
for fundExposures2
2010-08-05 16:39:33,363 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No column pruned
for fundExposures1
2010-08-05 16:39:33,363 [main] INFO 
org.apache.pig.impl.logicalLayer.optimizer.PruneColumns - No map keys pruned
for fundExposures1
2010-08-05 16:39:33,469 [main] WARN 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- Encountered Warning DID_NOT_FIND_LOAD_ONLY_MAP_PLAN 1 time(s).
2010-08-05 16:39:33,484 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MRCompiler$LastInputStreamingOptimizer
- Rewrite: POPackage-POForEach to POJoinPackage
2010-08-05 16:39:33,485 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MRCompiler$LastInputStreamingOptimizer
- Rewrite: POPackage-POForEach to POJoinPackage
2010-08-05 16:39:33,486 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MRCompiler$LastInputStreamingOptimizer
- Rewrite: POPackage-POForEach to POJoinPackage
2010-08-05 16:39:33,495 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MultiQueryOptimizer
- MR plan size before optimization: 5
2010-08-05 16:39:33,496 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MultiQueryOptimizer
- Merged 0 out of total 3 MR operators.
2010-08-05 16:39:33,496 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MultiQueryOptimizer
- MR plan size after optimization: 5
2010-08-05 16:39:33,501 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.AccumulatorOptimizer
- Reducer is to run in accumulative mode.
2010-08-05 16:39:33,502 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.AccumulatorOptimizer
- Reducer is to run in accumulative mode.
2010-08-05 16:39:34,465 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.JobControlCompiler
- Setting up single store job
2010-08-05 16:39:34,559 [Thread-12] WARN  org.apache.hadoop.mapred.JobClient
- Use GenericOptionsParser for parsing the arguments. Applications should
implement Tool for the same.
2010-08-05 16:39:35,585 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- Cannot get jobid for this job
2010-08-05 16:39:42,847 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- 0% complete
2010-08-05 16:39:55,415 [main] INFO 
org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher
- 5% 

Enabling LZO compression of map outputs in Cloudera Hadoop 0.20.1

2010-08-05 Thread Bobby Dennett
We are looking to enable LZO compression of the map outputs on our
Cloudera 0.20.1 cluster. It seems there are various sets of
instructions available and I am curious what your thoughts are
regarding which one would be best for our Hadoop distribution and OS
(Ubuntu 8.04 64-bit). In particular, hadoop-gpl-compression
(http://code.google.com/p/hadoop-gpl-compression) vs. hadoop-lzo
(http://github.com/kevinweil/hadoop-lzo).

Some of what appear to be the better instructions/guides out there:
* Josh Patterson's reply on June 25th to the Newbie to HDFS
compression thread --
http://mail-archives.apache.org/mod_mbox/hadoop-common-user/201006.mbox/%3caanlktileo-q8useip8y3na9pdyhlyufippr0in0lk...@mail.gmail.com%3e
* hadoop-gpl-compression FAQ --
http://code.google.com/p/hadoop-gpl-compression/wiki/FAQ
* Hadoop at Twitter (part 1): Splittable LZO Compression blog post
-- 
http://www.cloudera.com/blog/2009/11/hadoop-at-twitter-part-1-splittable-lzo-compression/

Thanks in advance,
-Bobby


Re: Enabling LZO compression of map outputs in Cloudera Hadoop 0.20.1

2010-08-05 Thread Arun C Murthy

Please take questions on Cloudera Distro to their internal lists.

On Aug 5, 2010, at 3:52 PM, Bobby Dennett wrote:


We are looking to enable LZO compression of the map outputs on our
Cloudera 0.20.1 cluster. It seems there are various sets of
instructions available and I am curious what your thoughts are
regarding which one would be best for our Hadoop distribution and OS
(Ubuntu 8.04 64-bit). In particular, hadoop-gpl-compression
(http://code.google.com/p/hadoop-gpl-compression) vs. hadoop-lzo
(http://github.com/kevinweil/hadoop-lzo).

Some of what appear to be the better instructions/guides out there:
* Josh Patterson's reply on June 25th to the Newbie to HDFS
compression thread --
http://mail-archives.apache.org/mod_mbox/hadoop-common-user/201006.mbox/%3caanlktileo-q8useip8y3na9pdyhlyufippr0in0lk...@mail.gmail.com%3e
* hadoop-gpl-compression FAQ --
http://code.google.com/p/hadoop-gpl-compression/wiki/FAQ
* Hadoop at Twitter (part 1): Splittable LZO Compression blog post
-- 
http://www.cloudera.com/blog/2009/11/hadoop-at-twitter-part-1-splittable-lzo-compression/

Thanks in advance,
-Bobby




Re: Enabling LZO compression of map outputs in Cloudera Hadoop 0.20.1

2010-08-05 Thread Josh Patterson
Bobby,

We're working hard to make compression easier, the biggest hurdle
currently is the licensing issues around the LZO codec libs (GPL,
which is not compatible with ASF bsd-style license).

Outside of making the changes to the mapred-site.xml file, with your
setup would do you view as the biggest pain point?

Josh Patterson
Cloudera

On Thu, Aug 5, 2010 at 6:52 PM, Bobby Dennett
bdennett+softw...@gmail.com wrote:
 We are looking to enable LZO compression of the map outputs on our
 Cloudera 0.20.1 cluster. It seems there are various sets of
 instructions available and I am curious what your thoughts are
 regarding which one would be best for our Hadoop distribution and OS
 (Ubuntu 8.04 64-bit). In particular, hadoop-gpl-compression
 (http://code.google.com/p/hadoop-gpl-compression) vs. hadoop-lzo
 (http://github.com/kevinweil/hadoop-lzo).

 Some of what appear to be the better instructions/guides out there:
 * Josh Patterson's reply on June 25th to the Newbie to HDFS
 compression thread --
 http://mail-archives.apache.org/mod_mbox/hadoop-common-user/201006.mbox/%3caanlktileo-q8useip8y3na9pdyhlyufippr0in0lk...@mail.gmail.com%3e
 * hadoop-gpl-compression FAQ --
 http://code.google.com/p/hadoop-gpl-compression/wiki/FAQ
 * Hadoop at Twitter (part 1): Splittable LZO Compression blog post
 -- 
 http://www.cloudera.com/blog/2009/11/hadoop-at-twitter-part-1-splittable-lzo-compression/

 Thanks in advance,
 -Bobby



Re: Enabling LZO compression of map outputs in Cloudera Hadoop 0.20.1

2010-08-05 Thread Bobby Dennett
Hi Josh,

No real pain points... just trying to investigate/research the best
way to create the necessary libraries and jar files to support LZO
compression in Hadoop. In particular, there are the 2 repositories
to build from and I am trying to find out if one should be used over
the other. For instance, in your previous posting, you refer to
hadoop-gpl-compression while the Twitter blog post from last year
mentions the Hadoop-LZO project. Briefly looking, it seems Hadoop-LZO
is preferable but we're curious if there are any caveats/gotchas we
should be aware of.

Thanks,
-Bobby

On Thu, Aug 5, 2010 at 15:59, Josh Patterson j...@cloudera.com wrote:
 Bobby,

 We're working hard to make compression easier, the biggest hurdle
 currently is the licensing issues around the LZO codec libs (GPL,
 which is not compatible with ASF bsd-style license).

 Outside of making the changes to the mapred-site.xml file, with your
 setup would do you view as the biggest pain point?

 Josh Patterson
 Cloudera

 On Thu, Aug 5, 2010 at 6:52 PM, Bobby Dennett
 bdennett+softw...@gmail.com wrote:
 We are looking to enable LZO compression of the map outputs on our
 Cloudera 0.20.1 cluster. It seems there are various sets of
 instructions available and I am curious what your thoughts are
 regarding which one would be best for our Hadoop distribution and OS
 (Ubuntu 8.04 64-bit). In particular, hadoop-gpl-compression
 (http://code.google.com/p/hadoop-gpl-compression) vs. hadoop-lzo
 (http://github.com/kevinweil/hadoop-lzo).

 Some of what appear to be the better instructions/guides out there:
 * Josh Patterson's reply on June 25th to the Newbie to HDFS
 compression thread --
 http://mail-archives.apache.org/mod_mbox/hadoop-common-user/201006.mbox/%3caanlktileo-q8useip8y3na9pdyhlyufippr0in0lk...@mail.gmail.com%3e
 * hadoop-gpl-compression FAQ --
 http://code.google.com/p/hadoop-gpl-compression/wiki/FAQ
 * Hadoop at Twitter (part 1): Splittable LZO Compression blog post
 -- 
 http://www.cloudera.com/blog/2009/11/hadoop-at-twitter-part-1-splittable-lzo-compression/

 Thanks in advance,
 -Bobby




Re: Enabling LZO compression of map outputs in Cloudera Hadoop 0.20.1

2010-08-05 Thread Todd Lipcon
On Thu, Aug 5, 2010 at 4:52 PM, Bobby Dennett bdenn...@gmail.com wrote:

 Hi Josh,

 No real pain points... just trying to investigate/research the best
 way to create the necessary libraries and jar files to support LZO
 compression in Hadoop. In particular, there are the 2 repositories
 to build from and I am trying to find out if one should be used over
 the other. For instance, in your previous posting, you refer to
 hadoop-gpl-compression while the Twitter blog post from last year
 mentions the Hadoop-LZO project. Briefly looking, it seems Hadoop-LZO
 is preferable but we're curious if there are any caveats/gotchas we
 should be aware of.


Yes, definitely use the hadoop-lzo project from github -- either from my
repo or from kevinweil's (the two are kept in sync)

The repo on Google Code has a number of known bugs, which is why we forked
it over to github last year.

-Todd

On Thu, Aug 5, 2010 at 15:59, Josh Patterson j...@cloudera.com wrote:
  Bobby,
 
  We're working hard to make compression easier, the biggest hurdle
  currently is the licensing issues around the LZO codec libs (GPL,
  which is not compatible with ASF bsd-style license).
 
  Outside of making the changes to the mapred-site.xml file, with your
  setup would do you view as the biggest pain point?
 
  Josh Patterson
  Cloudera
 
  On Thu, Aug 5, 2010 at 6:52 PM, Bobby Dennett
  bdennett+softw...@gmail.com bdennett%2bsoftw...@gmail.com wrote:
  We are looking to enable LZO compression of the map outputs on our
  Cloudera 0.20.1 cluster. It seems there are various sets of
  instructions available and I am curious what your thoughts are
  regarding which one would be best for our Hadoop distribution and OS
  (Ubuntu 8.04 64-bit). In particular, hadoop-gpl-compression
  (http://code.google.com/p/hadoop-gpl-compression) vs. hadoop-lzo
  (http://github.com/kevinweil/hadoop-lzo).
 
  Some of what appear to be the better instructions/guides out there:
  * Josh Patterson's reply on June 25th to the Newbie to HDFS
  compression thread --
 
 http://mail-archives.apache.org/mod_mbox/hadoop-common-user/201006.mbox/%3caanlktileo-q8useip8y3na9pdyhlyufippr0in0lk...@mail.gmail.com%3e
  * hadoop-gpl-compression FAQ --
  http://code.google.com/p/hadoop-gpl-compression/wiki/FAQ
  * Hadoop at Twitter (part 1): Splittable LZO Compression blog post
  --
 http://www.cloudera.com/blog/2009/11/hadoop-at-twitter-part-1-splittable-lzo-compression/
 
  Thanks in advance,
  -Bobby
 
 




-- 
Todd Lipcon
Software Engineer, Cloudera


Best way to reduce a 8-node cluster in half and get hdfs to come out of safe mode

2010-08-05 Thread Steve Kuo
As part of our experimentation, the plan is to pull 4 slave nodes out of a
8-slave/1-master cluster.  With replication factor set to 3, I thought
losing half of the cluster may be too much for hdfs to recover.  Thus I
copied out all relevant data from hdfs to local disk and reconfigure the
cluster.

The 4 slave nodes started okay but hdfs never left safe mode.  The nn.log
has the following line.  What is the best way to deal with this?  Shall I
restart the cluster with 8-node and then delete
/data/hadoop-hadoop/mapred/system?  Or shall I reformat hdfs?

Thanks.

2010-08-05 22:28:12,921 INFO
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.audit:
ugi=hadoop,hadoop   ip=/10.128.135.100  cmd=listStatus
src=/data/hadoop-hadoop/mapred/system   dst=nullperm=null
2010-08-05 22:28:12,923 INFO org.apache.hadoop.ipc.Server: IPC Server
handler 0 on 9000, call delete(/data/hadoop-hadoop/mapred/system, true) from
10.128.135.100:52368: error:
org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot delete
/data/hadoop-hadoop/mapred/system. Name node is in safe mode.
The reported blocks 64 needs additional 3 blocks to reach the threshold
0.9990 of total blocks 68. Safe mode will be turned off automatically.
org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot delete
/data/hadoop-hadoop/mapred/system. Name node is in safe mode.
The reported blocks 64 needs additional 3 blocks to reach the threshold
0.9990 of total blocks 68. Safe mode will be turned off automatically.
at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.deleteInternal(FSNamesystem.java:1741)
at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.delete(FSNamesystem.java:1721)
at
org.apache.hadoop.hdfs.server.namenode.NameNode.delete(NameNode.java:565)
at sun.reflect.GeneratedMethodAccessor13.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:512)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:968)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:964)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:962)