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From "Berk D. Demir" <...@mindcast.org>
Subject Re: Durability of HBase
Date Mon, 30 Nov 2009 08:36:16 GMT
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.

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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