Liu Shaohui created HBASE-11218:
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Summary: Data loss in HBase standalone mode
Key: HBASE-11218
URL: https://issues.apache.org/jira/browse/HBASE-11218
Project: HBase
Issue Type: Bug
Reporter: Liu Shaohui
Fix For: 0.99.0
Data loss in HBase standalone mode.
*How to produce it*
# Start HBase standalone mode.
# Create a table using hbase shell.
# Scan '.META.' and you will find data in meta table
# Kill the HBase process with -9 option
# Start the HBase agaion
# Scan '.META.' and you will find nothing in meta table.
*There are three main reasons.*
# FSDataOutputStream.sync should call flush() if the underlying wrapped stream
is not Syncable. See HADOOP-8861
# writeChecksum is ture in default LocalFileSystem and the
ChecksumFSOutputSummer will buffer the data, which make the waledits are not
written to os's filesystem with sync method immediately, and those edits will
be lost in regionserver's failover.
# The MiniZooKeeperCluster deletes the old zk data at startup which maye cause
data loss in meta table. The failover procedure is: split pre root
regionserver's hlog -> assign root -> split pre meta regionserver's hlog ->
assign meta -> split all other regionservers' hlogs -> assign other regions. If
there is no data in zookeeper, we will get null for root regionserver and then
assign root table. Some data in root table maybe be lost for some root's
WalEdits have not been splited and replayed. So does the Meta table.
I finished the patch for 0.94 and am working on the patch for trunk.
Suggestions are welcomed.
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