Thanks a lot for your reply, Daniel, very helpful. About (1) : I will consider this way, thanks. Also beside multiple clusters, are there any other options to do so? Thanks. About (2), if I understand correctly, HDFS used the quorum journal manager(QJM) for HA, and the client still only communicates with the active namenode, not both node, am I understanding right? Thanks.
On Fri, Jul 22, 2016 at 1:27 PM, Daniel Templeton <dan...@cloudera.com> wrote: > On 7/22/16 8:45 AM, Kun Ren wrote: > >> (1). How to create/start multiple namenodes? >> > > Just pretend like you have two separate HDFS clusters and set them up that > way. (That is actually what you have.) > > (2). Once I have multiple Namenodes running, do you think what is the >> best/simple way to change the HDFS client code to let the clients send the >> requests to a random Namenode? >> > > The client code is already built to try multiple NNs to handle HA. You can > look there for inspiration. If you want random, grab a random number and > mod it by the number of NNs, then use that as an index into the list of NNs. > > (3). I need to support the communication between the Namenodes, my current >> plan is to create one more protocol that supports the communication >> between >> the Namenodes, something like the clientProtocol and >> ClientDataNodeProtocol. Do you think is it easy to do so? Or do you have >> other suggestions to support the communication between the Namenodes? >> > > You will indeed need to define a new protocol. Not the easiest thing in > the world, but there are plenty of docs on protobuf. Good luck! > > Daniel >
