Need some clarification about fsck missing replicas

[Amith D K]

Hi ,



I need to know when the missing replicas in fsck is displayed



>From Hadoop Definitive guide 3 we can see



"Missing Replicas

    Threse are blocks with no replicas anywhere in the cluster."



page number 346 Chap 10 Administrating Hadoop.

If we check the code
NamenodeFsck#check() {
.
.
if(locs.length < targetFileReplication && locs.length>0) {
res.missingreplicas+=(targetFileReplication - locs.length );
res.numUnderReplicatedBlocks+=1;
.
.
}

currently from code i can makeout the number of replicas required to meet the 
expected replication.


1. By the definition from Definitive guide res.missingreplicas should be 
incremented when locs.length==0,
    I am not able makeout which one to follow ?

2. Should missing replicas be considered as UnderReplicatedBlocks while 
displaying in fsck ?

Thanks in Advance
Amith