[HDFS-15446] CreateSnapshotOp fails during edit log loading for /.reserved/raw/path with error java.io.FileNotFoundException: Directory does not exist: /.reserved/raw/path

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.2.0, 3.3.0
• Fix Version/s: 3.2.2, 3.3.1, 3.4.0
• Component/s: hdfs
• Labels: reserved-word snapshot
• Target Version/s: 3.4.0
• Hadoop Flags: Reviewed
• Assignee: Stephen O'Donnell
• Reporter: Srinivasu Majeti
• Created: 30/Jun/20 04:54
• Updated: 10/Jun/21 07:44
• Resolved: 04/Jul/20 07:38

Description

After allowing snapshot creation for a path say /app-logs , when we try to create snapshot on
/.reserved/raw/app-logs , its successful with snapshot creation but later when Standby Namenode is restarted and tries to load the edit record OP_CREATE_SNAPSHOT , we see it failing and Standby Namenode shuts down with an exception "ava.io.FileNotFoundException: Directory does not exist: /.reserved/raw/app-logs" .

Here are the steps to reproduce :

# hdfs dfs -ls /.reserved/raw/
Found 15 items
drwxrwxrwt   - yarn   hadoop          0 2020-06-29 10:27 /.reserved/raw/app-logs
drwxr-xr-x   - hive   hadoop          0 2020-06-29 10:29 /.reserved/raw/prod
++++++++++++++
[root@c3230-node2 ~]# hdfs dfsadmin -allowSnapshot /app-logs
Allowing snapshot on /app-logs succeeded
[root@c3230-node2 ~]# hdfs dfsadmin -allowSnapshot /prod
Allowing snapshot on /prod succeeded
++++++++++++++
# hdfs lsSnapshottableDir
drwxrwxrwt 0 yarn hadoop 0 2020-06-29 10:27 1 65536 /app-logs
drwxr-xr-x 0 hive hadoop 0 2020-06-29 10:29 1 65536 /prod
++++++++++++++
[root@c3230-node2 ~]# hdfs dfs -createSnapshot /.reserved/raw/app-logs testSS
Created snapshot /.reserved/raw/app-logs/.snapshot/testSS

Exception we see in Standby namenode while loading the snapshot creation edit record.

2020-06-29 10:33:25,488 ERROR namenode.NameNode (NameNode.java:main(1715)) - Failed to start namenode.
java.io.FileNotFoundException: Directory does not exist: /.reserved/raw/app-logs
        at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.valueOf(INodeDirectory.java:60)
        at org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.getSnapshottableRoot(SnapshotManager.java:259)
        at org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.createSnapshot(SnapshotManager.java:307)
        at org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.applyEditLogOp(FSEditLogLoader.java:772)
        at org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadEditRecords(FSEditLogLoader.java:257)