Hi Tao, No, you need to set mapred.local.dir in the mapred-site.xml with comma separated list of path to spread I/O .
On Mon, Dec 16, 2013 at 5:11 PM, Tao Xiao <[email protected]> wrote: > Thanks. > > In order to spread I/O among multiple disks, should I assign a > comma-separated list of directories which are located on different disks to > "hadoop.tmp.dir"？ > > for example, > > <property> > <name>hadoop.tmp.dir</name> > > <value>/mnt/disk1/hadoop_tmp_dir,/mnt/disk2/hadoop_tmp_dir,/mnt/disk3/hadoop_tmp_dir</value> > </property> > > > 2013/12/16 Shekhar Sharma <[email protected]> > >> hadoop.tmp.dir is a directory created on local file system >> For example if you have set hadoop.tmp.dir property to >> /home/training/hadoop >> >> This directory will be created when you format the namenode by running >> the command >> hadoop namenode -format >> >> When you open this folder >> >> >> you will see two subfolders dfs and mapred. >> >> the /home/training/hadoop/mapred folder will be on HDFS also >> >> Hope this clears >> Regards, >> Som Shekhar Sharma >> +91-8197243810 >> >> >> On Mon, Dec 16, 2013 at 1:42 PM, Dieter De Witte <[email protected]> >> wrote: >> > Hi, >> > >> > Make sure to also set mapred.local.dir to the same set of output >> > directories, this is were the intermediate key-value pairs are stored! >> > >> > Regards, Dieter >> > >> > >> > 2013/12/16 Tao Xiao <[email protected]> >> >> >> >> I have ten disks per node,and I don't know what value I should set to >> >> "hadoop.tmp.dir". Some said this property refers to a location in >> local disk >> >> while some other said it refers to a directory in HDFS. I'm confused, >> who >> >> can explain it ? >> >> >> >> I want to spread I/O since I have ten disks per node, so should I set a >> >> comma-separated list of directories (which are on different disks) to >> >> "hadoop.tmp.dir" ? >> > >> > >> > >
