[HDFS-1362] Provide volume management functionality for DataNode

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.23.0
• Fix Version/s: 2.7.0
• Component/s: datanode

Release Note

Based on the reconfiguration framework provided by HADOOP-7001, enable reconfigure the dfs.datanode.data.dir and add new volumes into service.

• Tags: datanode, volume, reconfigure
• Assignee: Wang Xu
• Reporter: Wang Xu
• Created: 29/Aug/10 15:53
• Updated: 24/Apr/15 23:23
• Resolved: 31/Oct/14 01:00

Description

The current management unit in Hadoop is a node, i.e. if a node failed, it will be kicked out and all the data on the node will be replicated.

As almost all SATA controller support hotplug, we add a new command line interface to datanode, thus it can list, add or remove a volume online, which means we can change a disk without node decommission. Moreover, if the failed disk still readable and the node has enouth space, it can migrate data on the disks to other disks in the same node.

A more detailed design document will be attached.

The original version in our lab is implemented against 0.20 datanode directly, and is it better to implemented it in contrib? Or any other suggestion?

Issue Links

• depends upon: HADOOP-7001 Allow configuration changes without restarting configured nodes
• is blocked by: HDFS-1405 Make FSVolumeSet in FSDataSet pluggable
• is blocked by: HADOOP-7001 Allow configuration changes without restarting configured nodes
• is duplicated by: HDFS-664 Add a way to efficiently replace a disk in a live datanode
• is duplicated by: HDFS-4239 Means of telling the datanode to stop using a sick disk
• is related to: HDFS-2137 Datanode Disk Fail Inplace
• is required by: HDFS-4239 Means of telling the datanode to stop using a sick disk

Sub-Tasks

• Refresh data volumes on DataNode based on configuration changes: Closed
• Dynamically add new volumes to DataStorage, formatted if necessary.: Closed
• Make FSDataset support adding data volumes dynamically: Closed
• Make FsDataset and DataStore support removing volumes.: Closed
• Add command line option to ask DataNode reload configuration.: Closed
• Avoid calling checkDisk when an HDFS volume is removed during a write.: Closed
• Make adding a new data directory to the DataNode an atomic operation and improve error handling: Closed
• Fix returning value of starting reconfiguration task: Closed
• Using Time.now() for recording start/end time of reconfiguration tasks: Closed
• Only keep successfully loaded volumes in the configuration.: Resolved
• Add documentation for hot swaping DataNode drives: Closed
• Test partial failures when loading / removing volumes.: Resolved