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From JQ Hadoop <jq.had...@gmail.com>
Subject Re: Durability of HBase
Date Tue, 01 Dec 2009 02:17:53 GMT
I wonder if you can point me to the message or the title of the
message. It seems that I cannot find the message ...


On Mon, Nov 30, 2009 at 4:36 PM, Berk D. Demir <bdd@mindcast.org> wrote:
> Short answer is "yes you can still lose data".
> It's about HDFS and HDFS-265 will solve this.
> Similar question was in the list a couple of days ago.
> Here's Ryan's answer.
> http://mail-archives.apache.org/mod_mbox/hadoop-hbase-user/200911.mbox/browser
> On Mon, Nov 30, 2009 at 00:18, JQ Hadoop <jq.hadoop@gmail.com> wrote:
>> I have a question regarding the durability of HBase. After I have put
>> a record to HBase and have received a confirmation of the put from the
>> region server (assuming both autoFlush and writeToWAL are set to
>> true), can I be sure that my record will be there no matter what? I've
>> checked the code and found that the region server will first append a
>> log record to WAL (a SequenceFile) and then may call the sync()
>> function; however, it appears to me that this does not guarantee the
>> log record is in HDFS even if the sync() function is called. That is
>> to say, in case of RegionServer crash, the records put into HBase may
>> be lost; am I missing anything?
>> Thanks,
>> -JQ

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