[jira] [Created] (HDFS-4868) Clean up error message when trying to snapshot using ViewFileSystem

["Stephen Chu (JIRA)" <ji...@apache.org>]

Stephen Chu created HDFS-4868:
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             Summary: Clean up error message when trying to snapshot using ViewFileSystem
                 Key: HDFS-4868
                 URL: https://issues.apache.org/jira/browse/HDFS-4868
             Project: Hadoop HDFS
          Issue Type: Improvement
          Components: snapshots
            Reporter: Stephen Chu
            Priority: Minor


Snapshots aren't supported for the ViewFileSystem. When users try to create a snapshot, they'll run into a message like the following:

{code}
schu-mbp:presentation schu$ hadoop fs -createSnapshot /user/schu
-createSnapshot: Fatal internal error
java.lang.UnsupportedOperationException: ViewFileSystem doesn't support createSnapshot
	at org.apache.hadoop.fs.FileSystem.createSnapshot(FileSystem.java:2285)
	at org.apache.hadoop.fs.shell.SnapshotCommands$CreateSnapshot.processArguments(SnapshotCommands.java:87)
	at org.apache.hadoop.fs.shell.Command.processRawArguments(Command.java:194)
	at org.apache.hadoop.fs.shell.Command.run(Command.java:155)
	at org.apache.hadoop.fs.FsShell.run(FsShell.java:255)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:84)
	at org.apache.hadoop.fs.FsShell.main(FsShell.java:305)
{code}

To make things more readable and avoid confusion, it would be helpful to clean up the error message stacktrace and just state that ViewFileSystem doesn't support createSnapshot, similar to what was done in HDFS-4846. The "fatal internal error" message is a bit scary and it might be useful to remove that message to avoid confusion from operators.

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