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From Yamini Joshi <yamini.1...@gmail.com>
Subject Re: Data Replication
Date Sun, 16 Oct 2016 03:44:40 GMT
So HDFS is for durability while replication is for availability? I'm
assuming that the client is unaware of the replicated instance and queries
the DB with no knowledge of which instance/table will return the result.

Best regards,
Yamini Joshi

On Thu, Oct 13, 2016 at 11:46 AM, Josh Elser <josh.elser@gmail.com> wrote:

> I'm not familiar with MongoDB. Perhaps someone else can confirm this for
> you.
>
> Yamini Joshi wrote:
>
>> So, can I say that if I have a table split across nodes (i.e. num
>> tablets > 1) and HDFS replication in my system, it is sort of equivalent
>> to a sharded and replicated mongo architecture?
>>
>> Best regards,
>> Yamini Joshi
>>
>> On Thu, Oct 13, 2016 at 11:06 AM, Josh Elser <josh.elser@gmail.com
>> <mailto:josh.elser@gmail.com>> wrote:
>>
>>     The Accumulo (Data Center) Replication feature is for having
>>     multiple active Accumulo clusters all containing the same data.
>>
>>     HDFS provides replication as a means for durability of the data it
>>     is storing. The files that Accumulo creates on one HDFS instance are
>>     replicated by HDFS. This does not help if your entire cluster become
>>     unavailable. That is what the data center replication Accumulo
>>     feature solves.
>>
>>     While both can be called "replication", they serve very different
>>     purposes.
>>
>>
>>     Yamini Joshi wrote:
>>
>>         Hello
>>
>>         I was going through some Accumulo docs and found out about
>>         replication.
>>         To enable replication,one needs to make some config settings as
>>         described in
>>         https://github.com/apache/accumulo/blob/master/docs/src/main
>> /asciidoc/chapters/replication.txt
>>         <https://github.com/apache/accumulo/blob/master/docs/src/mai
>> n/asciidoc/chapters/replication.txt>.
>>         I cannot seem to grasp the difference between this replication
>>         conf and
>>         the replication on HDFS level. What exactly is the use case for
>>         replication? Are the replicated instances visible to the clients?
>>
>>         Best regards,
>>         Yamini Joshi
>>
>>
>>

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