Re: Substriping support in ErasureCodeInterface

[Loic Dachary <loic@dachary.org>]

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Hi,

On 05/06/2015 14:02, Sindre Stene wrote:
> Is there, or is there planned support for substriping/subpacket support in ErasureCodeInterface ?

Not at the moment.

> Clarification; I am looking for a way to test a different erasure coding scheme, that (in addition to having multiple stripes) has substripes within those stripes, letting us further reduce the amount of chunks retrieved from the HDD. I have an implementation ready in C for the encoder/decoder etc. I am looking to plug that into Ceph through the ErasureCodeInterface.

https://github.com/ceph/ceph/blob/master/src/erasure-code/ErasureCodeInterface.h

> The principles involved (which I am sure you are familiar with) are similar to https://research.facebook.com/publications/1445994382319911/a-hitchhiker-s-guide-to-fast-and-efficient-data-reconstruction-in-erasure-coded-data-centers/ , but with more substripes (>4, < 256).

There is a declaration of intent for an hitchhiker plugin at http://tracker.ceph.com/issues/11268 but there is no progress yet.

> Can it currently be done without having to modify the Ceph code base ? (I am looking at master on ceph/ceph, and it seems to not be possible).
> Could I ask you to link me to the appropriate issue tracker / Jira / forum, if there is development going on already towards this goal? 

Why do you think the current interface is insufficient ? What would you need in addition ?

Cheers

> 
> Sincerely,
> Sindre B. Stene

-- 
Loïc Dachary, Artisan Logiciel Libre


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