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From lars hofhansl <la...@apache.org>
Subject Re: persistence in Hbase
Date Fri, 11 Jan 2013 03:54:46 GMT
Not entirely true, though.
Data is not sync'ed to disk, but only distributed to all HDFS replicas.
During a power outage event across all HDFS failure zones (such as a data center) you can
lose data.


-- Lars



----- Original Message -----
From: anil gupta <anilgupta84@gmail.com>
To: user@hbase.apache.org
Cc: 
Sent: Thursday, January 10, 2013 2:38 PM
Subject: Re: persistence in Hbase

Hi Mohammad,

If the Write Ahead Log(WAL) is "turned on" then in **NO** case data should
be lost. HBase is strongly-consistent. If you know of any case when WAL is
turned on and data is lost then IMO that's a Critical bug in HBase.

Thanks,
Anil Gupta

On Thu, Jan 10, 2013 at 7:37 AM, Mohit Anchlia <mohitanchlia@gmail.com>wrote:

> Data also gets written in WAL. See:
>
> http://hbase.apache.org/book/perf.writing.html
>
> On Thu, Jan 10, 2013 at 7:36 AM, ramkrishna vasudevan <
> ramkrishna.s.vasudevan@gmail.com> wrote:
>
> > Yes definitely you will get back the data.
> >
> > Please read the HBase Book that explains things in detail.
> > http://hbase.apache.org/book.html.
> >
> > Regards
> > Ram
> >
> >
> > On Thu, Jan 10, 2013 at 8:48 PM, Panshul Gupta <panshul007@gmail.com>
> > wrote:
> >
> >  > Hello,
> > >
> > > I was wondering if it is possible that I have data stored in Hbase
> tables
> > > on my 10 node cluster. I switch off (power down) my cluster. When I
> power
> > > up my cluster again, and run the HDFS and hadoop daemons, will the
> Hbase
> > > have my old data persisted in the form I left it?? or will I have to re
> > > import all the data??
> > >
> > > Thankyou for the help.
> > >
> > > --
> > > Regards,
> > > Panshul.
> > > http://about.me/panshulgupta
> > >
> >
>



-- 
Thanks & Regards,
Anil Gupta


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