Description
It would be useful if ViewFS had the ability to designate one FileSystem as a "primary"/"default" to fall back to in the case that an entry in the mount table is not found. Consider the situation when you have a mount table that looks like:
/data -> hdfs://nn1/data /logs -> hdfs://nn1/logs /user -> hdfs://nn1/user /remote -> hdfs://nn2/remote
nn1 here is being used as the primary, with a specific directory 'remote' being offloaded to another namenode. This works, but if we want to add another top-level directory to nn1, we have to update all of our client-side mount tables. Merge links (HADOOP-8298) could be used to achieve this but they do not seem to be coming soon; this special case of a default FS is much simpler - try to resolve through the VFS mount table, if not found, then resolve to the defaultFS.
There is a good discussion of this at https://issues.apache.org/jira/browse/HADOOP-13055?focusedCommentId=15733822&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15733822
Attachments
Issue Links
- duplicates
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HADOOP-13055 Implement linkMergeSlash and linkFallback for ViewFileSystem
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- Resolved
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- is related to
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HADOOP-8299 ViewFileSystem link slash mount point crashes with IndexOutOfBoundsException
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- Resolved
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- Resolved
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