[HDFS-12544] SnapshotDiff - support diff generation on any snapshot root descendant directory

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-beta1
• Fix Version/s: 3.0.0
• Component/s: hdfs
• Target Version/s: 3.0.0
• Assignee: Manoj Govindassamy
• Reporter: Manoj Govindassamy
• Created: 26/Sep/17 00:34
• Updated: 31/Oct/17 19:51
• Resolved: 25/Oct/17 18:17

Description

# hdfs snapshotDiff <snapshot_root_path> <from_snapshot_name> <to_snapshot_name>

Using snapshot diff command, we can generate a diff report between any two given snapshots under a snapshot root directory. The command today only accepts the path that is a snapshot root. There are many deployments where the snapshot root is configured at the higher level directory but the diff report needed is only for a specific directory under the snapshot root. In these cases, the diff report can be filtered for changes pertaining to the directory we are interested in. But when the snapshot root directory is very huge, the snapshot diff report generation can take minutes even if we are interested to know the changes only in a small directory. So, it would be highly performant if the diff report calculation can be limited to only the interesting sub-directory of the snapshot root instead of the whole snapshot root.

Issue Links

• is depended upon by: HADOOP-14983 DistCp diff option support for snapshot root descendant directories