[HDFS-5517] Lower the default maximum number of blocks per file

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.2.0
• Fix Version/s: 3.0.0-alpha2
• Component/s: namenode
• Labels: BB2015-05-TBR
• Target Version/s: 3.0.0-alpha2
• Hadoop Flags: Incompatible change
• Release Note: The default value of "dfs.namenode.fs-limits.max-blocks-per-file" has been reduced from 1M to 10K.
• Assignee: Aaron Myers
• Reporter: Aaron Myers
• Created: 15/Nov/13 02:13
• Updated: 01/Dec/16 01:04
• Resolved: 30/Nov/16 23:59

Description

We introduced the maximum number of blocks per file in HDFS-4305, but we set the default to 1MM. In practice this limit is so high as to never be hit, whereas we know that an individual file with 10s of thousands of blocks can cause problems. We should lower the default value, in my opinion to 10k.