Re: Motivation for a DHT ring

[jean paul]

Hi all,
Please, i'd like to discuss again this question:
*What is the motivation for choosing a DHT ring in cassandra? Why not use a
normal parallel or distributed file system that supports replication?*
@Utkarsh Sengar:
*Where in the Dynamo paper is such argumentation?*
Did you mean these paragraphs

The Google File System is another distributed file system built for
hosting the state of Google’s internal applications. GFS uses a
simple design with a single master server for hosting the entire
metadata and where the data is split into chunks and stored in
chunkservers.

distributed storage system designed to handle multiple
server failures

  --> *Question: Because of GFS is centralized, cassandra **With fault
tolerance and reliability, gives a faster lookup mechanism across various
nodes in a cluster ?*

Thank you so much for answers. It is very intersting for me.
Kind regards.







2016-06-30 18:49 GMT+01:00 Utkarsh Sengar :

> With fault tolerance and reliability, it also gives a faster lookup
> mechanism across various nodes in a cluster.
> Amazon's dynamo paper might be a better read to understand the reasoning
> behind a DHT based system: http://www.allthingsdistributed.com/
> files/amazon-dynamo-sosp2007.pdf
>
> On Wed, Jun 29, 2016 at 11:48 PM, Jens Rantil  wrote:
>
>> Some reasons I can come up with:
>> - it would be hard to have tunable read/consistencies/replicas when
>> interfacing with a file system.
>> - data locality support would require strong coupling to the distributed
>> file system interface (if at all possible given that certain sstables
>> should live on the same data node).
>> - operator complexity both administering a distributed file system as
>> well as a Cassandra cluster. This was a personal reason why I chose
>> Cassandra instead of HBase for a project.
>>
>> Cheers,
>> Jens
>>
>> Den ons 29 juni 2016 13:01jean paul  skrev:
>>
>>>
>>>
>>> 2016-06-28 22:29 GMT+01:00 jean paul :
>>>
 Hi all,

 Please, What is the motivation for choosing a DHT ring in cassandra?
 Why not use a normal parallel or distributed file system that supports
 replication?

 Thank you so much for clarification.

 Kind regards.

>>>
>>> --
>>
>> Jens Rantil
>> Backend Developer @ Tink
>>
>> Tink AB, Wallingatan 5, 111 60 Stockholm, Sweden
>> For urgent matters you can reach me at +46-708-84 18 32.
>>
>
>
>
> --
> Thanks,
> -Utkarsh
>

Re: Motivation for a DHT ring

[Utkarsh Sengar]

With fault tolerance and reliability, it also gives a faster lookup
mechanism across various nodes in a cluster.
Amazon's dynamo paper might be a better read to understand the reasoning
behind a DHT based system:
http://www.allthingsdistributed.com/files/amazon-dynamo-sosp2007.pdf

On Wed, Jun 29, 2016 at 11:48 PM, Jens Rantil  wrote:

> Some reasons I can come up with:
> - it would be hard to have tunable read/consistencies/replicas when
> interfacing with a file system.
> - data locality support would require strong coupling to the distributed
> file system interface (if at all possible given that certain sstables
> should live on the same data node).
> - operator complexity both administering a distributed file system as well
> as a Cassandra cluster. This was a personal reason why I chose Cassandra
> instead of HBase for a project.
>
> Cheers,
> Jens
>
> Den ons 29 juni 2016 13:01jean paul  skrev:
>
>>
>>
>> 2016-06-28 22:29 GMT+01:00 jean paul :
>>
>>> Hi all,
>>>
>>> Please, What is the motivation for choosing a DHT ring in cassandra? Why
>>> not use a normal parallel or distributed file system that supports
>>> replication?
>>>
>>> Thank you so much for clarification.
>>>
>>> Kind regards.
>>>
>>
>> --
>
> Jens Rantil
> Backend Developer @ Tink
>
> Tink AB, Wallingatan 5, 111 60 Stockholm, Sweden
> For urgent matters you can reach me at +46-708-84 18 32.
>



-- 
Thanks,
-Utkarsh

Re: Motivation for a DHT ring

[Jens Rantil]

Some reasons I can come up with:
- it would be hard to have tunable read/consistencies/replicas when
interfacing with a file system.
- data locality support would require strong coupling to the distributed
file system interface (if at all possible given that certain sstables
should live on the same data node).
- operator complexity both administering a distributed file system as well
as a Cassandra cluster. This was a personal reason why I chose Cassandra
instead of HBase for a project.

Cheers,
Jens

Den ons 29 juni 2016 13:01jean paul  skrev:

>
>
> 2016-06-28 22:29 GMT+01:00 jean paul :
>
>> Hi all,
>>
>> Please, What is the motivation for choosing a DHT ring in cassandra? Why
>> not use a normal parallel or distributed file system that supports
>> replication?
>>
>> Thank you so much for clarification.
>>
>> Kind regards.
>>
>
> --

Jens Rantil
Backend Developer @ Tink

Tink AB, Wallingatan 5, 111 60 Stockholm, Sweden
For urgent matters you can reach me at +46-708-84 18 32.

Re: Motivation for a DHT ring

[jean paul]

2016-06-28 22:29 GMT+01:00 jean paul :

> Hi all,
>
> Please, What is the motivation for choosing a DHT ring in cassandra? Why
> not use a normal parallel or distributed file system that supports
> replication?
>
> Thank you so much for clarification.
>
> Kind regards.
>