[HDFS-16942] Send error to datanode if FBR is rejected due to bad lease

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4.0, 3.3.6
• Fix Version/s: 3.4.0, 3.2.5, 3.3.6
• Component/s: datanode, namenode
• Labels: pull-request-available
• Target Version/s: 3.4.0, 3.3.6
• Hadoop Flags: Reviewed
• Assignee: Stephen O'Donnell
• Reporter: Stephen O'Donnell
• Created: 07/Mar/23 14:25
• Updated: 28/Jan/24 07:14
• Resolved: 11/Mar/23 17:45

Description

When a datanode sends a FBR to the namenode, it requires a lease to send it. On a couple of busy clusters, we have seen an issue where the DN is somehow delayed in sending the FBR after requesting the least. Then the NN rejects the FBR and logs a message to that effect, but from the Datanodes point of view, it thinks the report was successful and does not try to send another report until the 6 hour default interval has passed.

If this happens to a few DNs, there can be missing and under replicated blocks, further adding to the cluster load. Even worse, I have see the DNs join the cluster with zero blocks, so it is not obvious the under replication is caused by lost a FBR, as all DNs appear to be up and running.

I believe we should propagate an error back to the DN if the FBR is rejected, that way, the DN can request a new lease and try again.

Issue Links

• links to: GitHub Pull Request #5460
• links to: GitHub Pull Request #5478