Hi i have two questions regarding hdfs and jps utility I am new to Hadoop and started leraning hadoop from the past week
1.when ever i start start-all.sh and jps in console it showing the processes started *naidu@naidu:~/work/hadoop-1.0.4/bin$ jps* *22283 NameNode* *23516 TaskTracker* *26711 Jps* *22541 DataNode* *23255 JobTracker* *22813 SecondaryNameNode* *Could not synchronize with target* But along with the list of process stared it always showing *" Could not synchronize with target" *in the jps output. What is meant by "Could not synchronize with target"? Can some one explain why this is happening? 2.Is it possible to format namenode multiple times? When i enter the namenode -format command, it not formatting the name node and showing the following ouput. *naidu@naidu:~/work/hadoop-1.0.4/bin$ hadoop namenode -format* *Warning: $HADOOP_HOME is deprecated.* * * *13/05/01 12:08:04 INFO namenode.NameNode: STARTUP_MSG: * */************************************************************* *STARTUP_MSG: Starting NameNode* *STARTUP_MSG: host = naidu/127.0.0.1* *STARTUP_MSG: args = [-format]* *STARTUP_MSG: version = 1.0.4* *STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0 -r 1393290; compiled by 'hortonfo' on Wed Oct 3 05:13:58 UTC 2012* *************************************************************/* *Re-format filesystem in /home/naidu/dfs/namenode ? (Y or N) y* *Format aborted in /home/naidu/dfs/namenode* *13/05/01 12:08:05 INFO namenode.NameNode: SHUTDOWN_MSG: * */************************************************************* *SHUTDOWN_MSG: Shutting down NameNode at naidu/127.0.0.1* * * *************************************************************/* Can someone help me in understanding this? Why is it not possible to format name node multiple times? On Wed, May 1, 2013 at 8:14 AM, Sanjay Subramanian < [email protected]> wrote: > +1 agreed > > Also as a general script programming practice I check if the variables I > am going to use are NON empty before using them…nothing related to Hive > scripts > > If [ ${freq} == "" ] > then > echo "variable freq is empty…exiting" > exit 1 > Fi > > > > From: Anthony Urso <[email protected]> > Reply-To: "[email protected]" <[email protected]> > Date: Tuesday, April 30, 2013 7:20 PM > To: "[email protected]" <[email protected]>, sumit ghosh < > [email protected]> > Subject: Re: Variable resolution Fails > > Your shell is expanding the variable ${env:freq}, which doesn't exist > in the shell's environment, so hive is getting the empty string in that > place. If you are always intending to run your query like this, just use > ${freq} which will be expanded as expected by bash and then passed to hive. > > Cheers, > Anthony > > > On Tue, Apr 30, 2013 at 4:40 PM, sumit ghosh <[email protected]> wrote: > >> Hi, >> >> The following variable *freq* fails to resolve: >> >> bash-4.1$ export freq=MNTH >> bash-4.1$ echo $freq >> MNTH >> bash-4.1$ hive -e "select ${env:freq} as dr from dual" >> Logging initialized using configuration in >> file:/etc/hive/conf.dist/hive-log4j.properties >> Hive history >> file=/hadoop1/hive_querylog/sumighos/hive_job_log_sumighos_201304302321_1867815625.txt >> FAILED: ParseException line 1:8 cannot recognize input near 'as' 'dr' >> 'from' in select clause >> bash-4.1$ >> >> Here dual is a table with 1 row. >> What am I am doing wrong? When I try to resolve freq - it is empty!! >> >> $ hive -S -e "select '${env:freq}' as dr from dual" >> >> $ >> >> Thanks, >> Sumit >> > > > CONFIDENTIALITY NOTICE > ====================== > This email message and any attachments are for the exclusive use of the > intended recipient(s) and may contain confidential and privileged > information. Any unauthorized review, use, disclosure or distribution is > prohibited. If you are not the intended recipient, please contact the > sender by reply email and destroy all copies of the original message along > with any attachments, from your computer system. If you are the intended > recipient, please be advised that the content of this message is subject to > access, review and disclosure by the sender's Email System Administrator. >
