In NN many deamons will run. For replicating the blocks from one DN to other DN when there is no enough replications. SafeMode monitering, LeaseManager & and will also maintain the Blocks to machineList mappings in memory, HeartbeatMonitoring, IPC handlers......etc.
In JT also there are many deamons like this. If you are not dealing with very less files then normal configuration is enough. But you should configure enough memory for running the NN and JT.This always will comes under your usage. For better understanding, I would suggest you to go through the Hadoop Deffenitive Guide. All this details has been documented very well. Regards, Uma ----- Original Message ----- From: praveenesh kumar <praveen...@gmail.com> Date: Thursday, September 22, 2011 11:45 am Subject: Re: Can we replace namenode machine with some other machine ? To: common-user@hadoop.apache.org > But apart from storing metadata info, Is there anything more NN/JT > machinesare doing ?? . > So I can say I can survive with poor NN if I am not dealing with > lots of > files in HDFS ? > > On Thu, Sep 22, 2011 at 11:08 AM, Uma Maheswara Rao G 72686 < > mahesw...@huawei.com> wrote: > > > By just changing the configs will not effect your data. You need > to restart > > your DNs to connect to new NN. > > > > For the second question: > > It will again depends on your usage. If your files will more in > DFS then > > NN will consume more memory as it needs to store all the > metadata info of > > the files in NameSpace. > > > > If your files are more and more then it is recommended that > dont put the > > NN and JT in same machine. > > > > Coming to DN case: Configured space will used for storing the block > > files.Once it is filled the space then NN will not select this > DN for > > further writes. So, if one DN has less space should fine than > less space for > > NN in big clusters. > > > > Configuring good configuration DN which has very good amount of > space. And > > NN has less space to store your files metadata info then its of > no use to > > have more space in DNs right :-) > > > > > > Regards, > > Uma > > ----- Original Message ----- > > From: praveenesh kumar <praveen...@gmail.com> > > Date: Thursday, September 22, 2011 10:42 am > > Subject: Re: Can we replace namenode machine with some other > machine ? > > To: common-user@hadoop.apache.org > > > > > If I just change configuration settings in slave machines, > Will it > > > effectany of the data that is currently residing in the > cluster ?? > > > > > > And my second question was... > > > Do we need the master node (NN/JT hosting machine) to have good > > > configuration than our slave machines(DN/TT hosting machines). > > > > > > Actually my master node is a weaker machine than my slave > > > machines,because I > > > am assuming that master machines does not do much additional work, > > > and its > > > okay to have a weak machine as master. > > > Now I have a new big server machine just being added to my > > > cluster. So I am > > > thinking shall I make this new machine as my new master(NN/JT) or > > > just add > > > this machine as slave ? > > > > > > Thanks, > > > Praveenesh > > > > > > > > > On Thu, Sep 22, 2011 at 10:20 AM, Uma Maheswara Rao G 72686 < > > > mahesw...@huawei.com> wrote: > > > > > > > You copy the same installations to new machine and change ip > > > address.> After that configure the new NN addresses to your > > > clients and DNs. > > > > > > > > >Also Does Namenode/JobTracker machine's configuration needs to > > > be better > > > > >than datanodes/tasktracker's ?? > > > > I did not get this question. > > > > > > > > Regards, > > > > Uma > > > > > > > > ----- Original Message ----- > > > > From: praveenesh kumar <praveen...@gmail.com> > > > > Date: Thursday, September 22, 2011 10:13 am > > > > Subject: Can we replace namenode machine with some other > machine ? > > > > To: common-user@hadoop.apache.org > > > > > > > > > Hi all, > > > > > > > > > > Can we replace our namenode machine later with some other > > > machine. ? > > > > > Actually I got a new server machine in my cluster and now > I want > > > > > to make > > > > > this machine as my new namenode and jobtracker node ? > > > > > Also Does Namenode/JobTracker machine's configuration > needs to be > > > > > betterthan datanodes/tasktracker's ?? > > > > > > > > > > How can I achieve this target with least overhead ? > > > > > > > > > > Thanks, > > > > > Praveenesh > > > > > > > > > > > > > > >
