[HDFS-15200] Delete Corrupt Replica Immediately Irrespective of Replicas On Stale Storage

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 3.3.0, 3.2.3
• Hadoop Flags: Reviewed
• Assignee: Ayush Saxena
• Reporter: Ayush Saxena
• Created: 02/Mar/20 12:13
• Updated: 10/Jun/21 07:44
• Resolved: 19/Mar/20 17:18

Description

Presently invalidateBlock(..) before adding a replica into invalidates, checks whether any block replica is on stale storage, if any replica is on stale storage, it postpones deletion of the replica.
Here :

   // Check how many copies we have of the block
    if (nr.replicasOnStaleNodes() > 0) {
      blockLog.debug("BLOCK* invalidateBlocks: postponing " +
          "invalidation of {} on {} because {} replica(s) are located on " +
          "nodes with potentially out-of-date block reports", b, dn,
          nr.replicasOnStaleNodes());
      postponeBlock(b.getCorrupted());
      return false;

In case of corrupt replica, we can skip this logic and delete the corrupt replica immediately, as a corrupt replica can't get corrected.

One outcome of this behavior presently is namenodes showing different block states post failover, as:
If a replica is marked corrupt, the Active NN, will mark it as corrupt, and mark it for deletion and remove it from corruptReplica's and excessRedundancyMap.
If before the deletion of replica, Failover happens.
The standby Namenode will mark all the storages as stale.
Then will start processing IBR's, Now since the replica's would be on stale storage, it will skip deletion, and removal from corruptReplica's
Hence both the namenode will show different numbers and different corrupt replicas.