[HDFS-9406] FSImage may get corrupted after deleting snapshot

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.6.0
• Fix Version/s: 2.8.0, 2.7.3, 3.0.0-alpha1
• Component/s: namenode

Environment

CentOS 6 amd64, CDH 5.4.4-1
2xCPU: Intel(R) Xeon(R) CPU E5-2640 v3
Memory: 32GB
Namenode blocks: ~700_000 blocks, no HA setup

• Hadoop Flags: Reviewed
• Assignee: Yongjun Zhang
• Reporter: Stanislav Antic
• Created: 10/Nov/15 11:07
• Updated: 01/Feb/18 17:35
• Resolved: 01/Feb/16 23:42

Description

FSImage corruption happened after HDFS snapshots were taken. Cluster was not used
at that time.

When namenode restarts it reported NULL pointer exception:

15/11/07 10:01:15 INFO namenode.FileJournalManager: Recovering unfinalized segments in /tmp/fsimage_checker_5857/fsimage/current
15/11/07 10:01:15 INFO namenode.FSImage: No edit log streams selected.
15/11/07 10:01:18 INFO namenode.FSImageFormatPBINode: Loading 1370277 INodes.
15/11/07 10:01:27 ERROR namenode.NameNode: Failed to start namenode.
java.lang.NullPointerException
        at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.addChild(INodeDirectory.java:531)
        at org.apache.hadoop.hdfs.server.namenode.FSImageFormatPBINode$Loader.addToParent(FSImageFormatPBINode.java:252)
        at org.apache.hadoop.hdfs.server.namenode.FSImageFormatPBINode$Loader.loadINodeDirectorySection(FSImageFormatPBINode.java:202)
        at org.apache.hadoop.hdfs.server.namenode.FSImageFormatProtobuf$Loader.loadInternal(FSImageFormatProtobuf.java:261)
        at org.apache.hadoop.hdfs.server.namenode.FSImageFormatProtobuf$Loader.load(FSImageFormatProtobuf.java:180)
        at org.apache.hadoop.hdfs.server.namenode.FSImageFormat$LoaderDelegator.load(FSImageFormat.java:226)
        at org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:929)
        at org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:913)
        at org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImageFile(FSImage.java:732)
        at org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:668)
        at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:281)
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFSImage(FSNamesystem.java:1061)
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFromDisk(FSNamesystem.java:765)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:584)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:643)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:810)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:794)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1487)
        at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1553)
15/11/07 10:01:27 INFO util.ExitUtil: Exiting with status 1

Corruption happened after "07.11.2015 00:15", and after that time blocks ~9300 blocks were invalidated that shouldn't be.
After recovering FSimage I discovered that around ~9300 blocks were missing.

I also attached log of namenode before and after corruption happened.

Issue Links

• is duplicated by: HDFS-9697 NN fails to restart due to corrupt fsimage caused by snapshot handling
• relates to: HDFS-13101 Yet another fsimage corruption related to snapshot
• relates to: HDFS-9696 Garbage snapshot records lingering forever