> > 2. how do you dynamically add and remove nodes in the cluser without > disturbing the existing map-reduce jobs (on EC2).
Are there datanodes and tasktrackers running on the same node as the regionserver? If so, it may be a little tricky coordinating them all. You could try shutting down the regionserver with a ./bin/hbase-daemon.sh regionserver stop (IIRC) and then just let the server go. Will this cause any loss of data.? How will the data loss be handled. On Wed, May 6, 2009 at 8:42 PM, stack <[email protected]> wrote: > On Wed, May 6, 2009 at 3:08 AM, Rakhi Khatwani <[email protected] > >wrote: > > > > > 1. i wanna scan a table, but the table is really huge. so i want the > result > > of the scan to some file so that i can analyze it. how do we go about > it??? > > > > > If your table is really huge, I presume your scan output huge too. > > You should write a MapReduce job. See TableInputFormat in the hbase mapred > package. See RowCounter in same package for an example pulling rows in a > MR > job from hbase. > > > > > > > 2. how do you dynamically add and remove nodes in the cluser without > > disturbing the existing map-reduce jobs (on EC2). > > > > Are there datanodes and tasktrackers running on the same node as the > regionserver? If so, it may be a little tricky coordinating them all. You > could try shutting down the regionserver with a ./bin/hbase-daemon.sh > regionserver stop (IIRC) and then just let the server go. > > > > > > > > 3. suppose my dfs replication is 3. (which implies that i have 3 copies > of > > data in some other location). how do i access other two copies. or how do > i > > find out in which machines are the other copies kept? > > > > A file is made of blocks in hdfs. Its the blocks that are replicated. To > see where the replicas are, you could enable debug logging. You might be > able to see where all are in the hdfs UI, I'm not sure. > > > > > > > > 4. If my hbase master fails, is there any way i can set another node as > my > > hbase master without disturbing my current map-reduce jobs?? > > > > Coming in 0.20.0 hbase. > > St.Ack >
