[HDFS-1539] prevent data loss when a cluster suffers a power loss

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.23.0, 1.1.1
• Component/s: datanode, hdfs-client, namenode
• Hadoop Flags: Reviewed
• Assignee: Dhruba Borthakur
• Reporter: Dhruba Borthakur
• Created: 16/Dec/10 00:06
• Updated: 02/Oct/14 17:55
• Resolved: 04/Jan/11 19:11

Description

we have seen an instance where a external outage caused many datanodes to reboot at around the same time. This resulted in many corrupted blocks. These were recently written blocks; the current implementation of HDFS Datanodes do not sync the data of a block file when the block is closed.

1. Have a cluster-wide config setting that causes the datanode to sync a block file when a block is finalized.
2. Introduce a new parameter to the FileSystem.create() to trigger the new behaviour, i.e. cause the datanode to sync a block-file when it is finalized.
3. Implement the FSDataOutputStream.hsync() to cause all data written to the specified file to be written to stable storage.

Issue Links

• relates to: HDFS-5042 Completed files lost after power failure