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From: Brian Bockelman <bbockelm@cse.unl.edu>
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Subject: Re: concurrent write [ is it defined and consistent ? ]
Date: Tue, 1 Dec 2009 08:18:48 -0600
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I double checked, and it appears that the answer you are looking for is =
in a funny section ("Data replication"):

"Files in HDFS are write-once and have strictly one writer at any time. =
"
"There is a plan to support appending-writes to files in the future."

So, there are no concurrent writes, but there are future plans for =
appends (currently in trunk).

Brian

On Dec 1, 2009, at 8:16 AM, Krishna Kumar wrote:

> It doesn't give answer to my query .
>=20
> Thanks and Best Regards,
> Krishna Kumar
> Senior Storage Engineer=20
> Why do we have to die? If we had to die, and everything is gone after
> that, then nothing else matters on this earth - everything is =
temporary,
> at least relative to me.
>=20
>=20
> -----Original Message-----
> From: Brian Bockelman [mailto:bbockelm@cse.unl.edu]=20
> Sent: Tuesday, December 01, 2009 7:32 PM
> To: common-user@hadoop.apache.org
> Subject: Re: concurrent write [ is it defined and consistent ? ]
>=20
> Hey Krishna,
>=20
> You might benefit from the HDFS design document:
>=20
> http://hadoop.apache.org/common/docs/current/hdfs_design.html
>=20
> Let us know if it is missing important information.
>=20
> Brian
>=20
> On Dec 1, 2009, at 7:59 AM, Krishna Kumar wrote:
>=20
>> Dear all,
>>=20
>>=20
>>=20
>> Can anybody tell me how concurrent write happens in HDFS ?
>>=20
>>=20
>>=20
>> Thanks and Best Regards,
>>=20
>> Krishna Kumar
>>=20
>> Senior Storage Engineer=20
>>=20
>> Why do we have to die? If we had to die, and everything is gone after
>> that, then nothing else matters on this earth - everything is
> temporary,
>> at least relative to me.
>>=20
>>=20
>>=20
>>=20
>>=20
>>=20
>>=20
>>=20
>> DISCLAIMER:=20
>>=20
> =
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