Well, the documentation is more explicite. Specifies the percentage of blocks that should satisfy the minimal replication requirement defined by* dfs.namenode.replication.min*.
Which happens to be 1 by default but doesn't need to stay that way. Regards Bertrand On Wed, Jan 30, 2013 at 5:45 PM, Nan Zhu <zhunans...@gmail.com> wrote: > I think Chen is asking replication lost, > > so, according to Harsh's reply, in safe mode, NN will know all blocks > which has less replications than 3(by default setup) but no less than 1, > and after getting out from safe mode, it will instruct the real replicating > works? Hope I understand it correctly > > Best, > > -- > Nan Zhu > School of Computer Science, > McGill University > > > On Wednesday, 30 January, 2013 at 11:39 AM, Harsh J wrote: > > Yes, if there are missing blocks (i.e. all replicas lost), and the > block availability threshold is set to its default of 0.999f (99.9% > availability required), then NN will not come out of safemode > automatically. You can control this behavior by configuring > dfs.namenode.safemode.threshold. > > On Wed, Jan 30, 2013 at 10:06 PM, Chen He <airb...@gmail.com> wrote: > > Hi Harsh > > I have a question. How namenode gets out of safemode in condition of data > blocks lost, only administrator? Accordin to my experiences, the NN (0.21) > stayed in safemode about several days before I manually turn safemode off. > There were 2 blocks lost. > > Chen > > > On Wed, Jan 30, 2013 at 10:27 AM, Harsh J <ha...@cloudera.com> wrote: > > > NN does recalculate new replication work to do due to unavailable > replicas ("under-replication") when it starts and receives all block > reports, but executes this only after out of safemode. When in > safemode, across the HDFS services, no mutations are allowed. > > On Wed, Jan 30, 2013 at 8:34 AM, Nan Zhu <zhunans...@gmail.com> wrote: > > Hi, all > > I'm wondering if HDFS is stopped, and some of the machines of the > cluster > are moved, some of the block replication are definitely lost for moving > machines > > when I restart the system, will the namenode recalculate the data > distribution? > > Best, > > -- > Nan Zhu > School of Computer Science, > McGill University > > > > > -- > Harsh J > > > > > -- > Harsh J > > >