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From Jean-Daniel Cryans <jdcry...@apache.org>
Subject Re: Does HTable.put() guaranty that data are effectively written?
Date Mon, 02 Aug 2010 17:22:39 GMT
HDFS started supporting fsSync in the 0.20-append branch (no release
yet) and 0.21.0 so data loss is expect in 0.20 (e.g. latest puts
aren't durable). See Todd's presentation for more background
information (starts at slide #16):
http://www.cloudera.com/blog/2010/03/hbase-user-group-9-hbase-and-hdfs/

If you which to use a "durable" hbase, you can use the latest HBase
0.89 (available on the website) along with a snapshot of Hadoop's
0.20-append branch. Alternatively, you can also use Cloudera's CDH3b2
which has both (I don't work for them, but it's probably just easier
to checkout at the moment).

J-D

On Mon, Aug 2, 2010 at 10:12 AM, Vincent Barat <vbarat@ubikod.com> wrote:
>  Hi,
>
> I have a simple Java program that write data into a set of HBase tables
> using the HTable().put() call and an infinite number of retries (in order to
> block when HBase fails and restart when it is up again, and thus guaranty
> that my data are written sooner or later).
>
> My cluster is a test cluster of 2 regionservers running HBase 0.20.3.
>
> During one (1) regionserver failure, I experienced the following issue: all
> the data I write are lost, with no exception and no error reported (the call
> act as if everything was ok).
>
> If I shut both regionservers down, I got my exception and errors and my code
> work fine (it blocks and restarts when hbase is up again).
>
> So my question is: is it a known problem ? Isn't HTable().put() supposed to
> guaranty that the data are correctly written when it returns with no failure
> ?
>
> Regards,
>
>

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