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From <Milind.Bhandar...@emc.com>
Subject Re: Strategy Of Replica
Date Tue, 11 Oct 2011 17:25:36 GMT
Replication policy in HDFS is pluggable, since hadoop 0.21:

https://issues.apache.org/jira/browse/HDFS-385


- Milind


On 10/10/11 10:26 PM, "Uma Maheswara Rao G 72686" <maheswara@huawei.com>
wrote:

>To get the best performance from Hadoop, we can configure network
>topology.
>Based on that, it will apply RackAwareness algorithms and write/read the
>files.
>  Also HDFS-2246 will improve performance by reading directly local
>replicas. 
>
>If you have good algorithm and will get good performance than this
>current algorithms, please file a JIRA with your proposed strategy and
>design doc. :-)
>
>Thanks & Regards,
>Uma
>
>----- Original Message -----
>From: gschen <gongsuochen@yahoo.com.cn>
>Date: Tuesday, October 11, 2011 9:26 am
>Subject: Re: Strategy Of Replica
>To: common-dev@hadoop.apache.org
>
>> On 2011/10/11 11:13, Uma Maheswara Rao G 72686 wrote:
>> > I did not get your proposed strategy implementations.
>> >
>> > Note that, already you can set the replication levels for files.
>> If you set less replication, then obviously your perf and space
>> will get benefits and also risk will be high in this case. I think
>> we can manage your requirements using that replication factor.
>> Your expectations are something different that this?
>> >
>> > Regards,
>> > Uma
>> > ----- Original Message -----
>> > From: gschen<gongsuochen@yahoo.com.cn>
>> > Date: Tuesday, October 11, 2011 8:14 am
>> > Subject: Strategy Of Replica
>> > To: "common-dev@hadoop.apache.org"<common-dev@hadoop.apache.org>
>> >
>> >> Hi guys,
>> >> What do you think of the strategy of replication in hdfs? How about
>> >> the
>> >> customized strategy that users customized their strategy of
>> >> replication
>> >> such as price, performance and so on?
>> >>
>> >> Thank you in advance.
>> >>
>> Thanks for your reply. In hdfs only one thing we can do is that we
>> could 
>> set replication factor to change replication  strategy, but we can
>> not 
>> change where the block is stored and what type of storage that we
>> stored 
>> the data. Just think this  case: In order to improve the
>> downloading 
>> speed, I can choose my block replication near my location or near
>> someone's location. I mean that users could have more option to
>> decide 
>> their block replication strategy.
>> 
>


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