Interesting. I thought that the write would fail in case if # of nodes downs is greater than min-replication property. So in reality we only get a warning while writing (and a info message through fsck.)
Regards, Shahab On Fri, Sep 19, 2014 at 9:26 AM, Abirami V <abiramipand...@gmail.com> wrote: > You will get under replicated block and missing replicas when you run > hdfs fsck / > > you may see info like the following > > Under replicated blk_-4791859336845413240_1544. Target Replicas > is 3 but found 2 replica(s). > > > > On Fri, Sep 19, 2014 at 5:36 AM, adarsh deshratnam < > adarsh.deshrat...@gmail.com> wrote: > >> 1. *How hadoop will take care of balancing of replicas as the required >> replicas are 3 , but we have only 2 data nodes up and running.* >> >> *Ans:* As here the replication factor is three. The data block will be >> replicated three time within 2 nodes. Block replication is random. >> >> *2. What happens when we try to write new data into hdfs at this point >> of time ? whether the write would be successful with only 2 data nodes and >> replication factor 3 or it returns any error message?* >> *Ans:*It will write successfully. >> >> >> For further info please refer below link: >> http://hadoop.apache.org/docs/r1.2.1/hdfs_design.html >> >> >> Thanks, >> Adarsh D >> >> On Fri, Sep 19, 2014 at 5:46 PM, Raghavendra Chandra < >> raghavchandra.learn...@gmail.com> wrote: >> >>> Hi All, >>> >>> I have one very basic query regarding the replication factor in HDFS. >>> >>> Scenario: >>> >>> I have 4 node cluster : 3 data nodes and 1 master node. >>> >>> The replication factor is 3. So ideally each data node would get one >>> replica . >>> >>> Assume that meanwhile one of the data node went down. >>> >>> so ideally we will be having 2 data nodes. >>> >>> Queries: >>> >>> 1. How hadoop will take care of balancing of replicas as the required >>> replicas are 3 , but we have only 2 data nodes up and running. >>> >>> 2. What happens when we try to write new data into hdfs at this point >>> of time ? whether the write would be successful with only 2 data nodes and >>> replication factor 3 or it returns any error message? >>> >>> >>> These queries might be simple, but it would be really helpful if some >>> one can answer. >>> >>> Thanks and regards, >>> Raghav Chandra >>> >>> >> >
