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From "Jean-Marc Spaggiari (JIRA)" <j...@apache.org>
Subject [jira] [Issue Comment Deleted] (HBASE-11218) Data loss in HBase standalone mode
Date Fri, 23 May 2014 15:47:02 GMT

     [ https://issues.apache.org/jira/browse/HBASE-11218?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jean-Marc Spaggiari updated HBASE-11218:
----------------------------------------

    Comment: was deleted

(was: [~nkeywal]
{quote}
I'm curious, why is it an issue for you?
{quote}
We use the standalone hbase in our onebox test env. In this env, we start the application
and other services (eg, hbase, zookeeper) that it depends on in a machine, , then do many
end-to-end logical and failure tests. So it is  important  to keep data durability in some
level. Data loss in standalone mode give a not good impression of HBase to out users.

{quote}
On the patch, will this slow down the tests?
{quote}
I will do a comparison and show the data later.
)

> 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
>            Assignee: Liu Shaohui
>             Fix For: 0.99.0
>
>         Attachments: HBASE-11218-trunk-v1.diff
>
>
> 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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