Any other ideas?
On Sun, Dec 22, 2013 at 10:38 PM, Dhaivat Pandya <dhaivatpan...@gmail.com>wrote: > I understand that that is how the port is *later* retrieved, but how does > the namenode know the port in the first place? i.e. if the datanode sends a > packet to the namenode, how does the namenode know what port # the datanode > server is running on? > > > On Sun, Dec 22, 2013 at 10:28 PM, Shekhar Sharma <shekhar2...@gmail.com>wrote: > >> Check the version file >> During the startup Datanode sends out a heart beat signal and NN >> assigns a storageID for it which is unique for every datanode. >> Using the storage id it identify the ip and port of a datanode >> Regards, >> Som Shekhar Sharma >> +91-8197243810 >> >> >> On Mon, Dec 23, 2013 at 9:41 AM, Dhaivat Pandya <dhaivatpan...@gmail.com> >> wrote: >> > Hi, >> > >> > I'm currently trying to build a cache layer that should sit "on top" of >> the >> > datanode. Essentially, the namenode should know the port number of the >> > cache layer instead of that of the datanode (since the namenode then >> relays >> > this information to the default HDFS client). All of the communication >> > between the datanode and the namenode currently flows through my cache >> > layer (including heartbeats, etc.) >> > >> > *First question*: is there a way to tell the namenode where a datanode >> > should be? Any way to trick it into thinking that the datanode is on a >> port >> > number where it actually isn't? As far as I can tell, the port number is >> > obtained from the DatanodeId object; can this be set in the >> configuration >> > so that the port number derived is that of the cache layer? >> > >> > I spent quite a bit of time on the above question and I could not find >> any >> > sort of configuration option that would let me do that. So, I delved >> into >> > the HDFS source code and tracked down the DatanodeRegistration class. >> > However, I can't seem to find out *how* the NameNode figures out the >> > Datanode's port number or if I could somehow change the packets to >> reflect >> > the port number of cache layer? *Second question: *how does the namenode >> > figure out a newly-registered Datanode's port number? >> > >> > Thank you, >> > >> > Dhaivat >> > >
