[HADOOP-171] need standard API to set dfs replication = high

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Affects Version/s: 0.2.0
• Assignee: Konstantin Shvachko
• Reporter: Doug Cutting
• Created: 27/Apr/06 06:24
• Updated: 08/Jul/09 16:41
• Resolved: 27/Apr/06 07:27

Description

There should be a standard way to indicate that files should be highly replicated, appropriate for files that all nodes will read. This should be settable both on file creation and for already-existing files. Perhaps specifying a particular replication value, like Short.MAX_VALUE, or zero, can be used to signal this. The level should not be constant, but should be relative to the cluster size and network topography. If more nodes are added or if nodes are deleted, the actual replication count should increase or decrease.

Initially, all that is needed is an API to specify this. It could initially be implemented with a constant (e.g., 10) or with something related to the number of datanodes (sqrt?), and needn't auto-adjust as the cluster size changes That is only the long-term goal.

When JobClient copies job files (job.xml & job.jar) into the job's filesystem, it should specify this replication level.

Issue Links

• duplicates: HADOOP-130 Should be able to specify "wide" or "full" replication
• is related to: HADOOP-170 setReplication and related bug fixes