questions about erasure coded pool and rados

questions about erasure coded pool and rados

[yue longguang]

1. why erasure coded pool does not work with rbd?
2. i used rados command to put a file into erasue coded pool,then rm
it. why the file remains on osd's backend fs all the time?
3. what is the best use case with erasure coded pool?

4. command of 'rados ls' is to list objects, where are the object-name stored?
5.when a rbd file is put on erasure coded pool, where is the
infomation(rbd name) of the rbd stored?

thanks

Re: questions about erasure coded pool and rados

[Owen Synge]

An erasure encoded pool cannot be accessed directly using rbd. For this
reason we need a cache pool and an erasure pool. This not only allows
supporting rbd but increases performance.


http://karan-mj.blogspot.de/2014/04/erasure-coding-in-ceph.html
http://docs.ceph.com/docs/master/rados/operations/pools/
http://ceph.com/docs/master/rados/operations/cache-tiering/

Good luck

Owen

On 10/17/2014 12:13 PM, yue longguang wrote:
> 1. why erasure coded pool does not work with rbd?
> 2. i used rados command to put a file into erasue coded pool,then rm
> it. why the file remains on osd's backend fs all the time?
> 3. what is the best use case with erasure coded pool?
> 
> 4. command of 'rados ls' is to list objects, where are the object-name stored?
> 5.when a rbd file is put on erasure coded pool, where is the
> infomation(rbd name) of the rbd stored?
> 
> thanks
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: questions about erasure coded pool and rados

[Loic Dachary]

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Hi,

In addition to Owen's answer:

On 17/10/2014 03:13, yue longguang wrote:
> 1. why erasure coded pool does not work with rbd?
> 2. i used rados command to put a file into erasue coded pool,then rm
> it. why the file remains on osd's backend fs all the time?

They will go away at some point but they are not removed from the file system immediately. There is however no risk that they re-appear in ceph ;-)

Cheers

> 3. what is the best use case with erasure coded pool?
> 4. command of 'rados ls' is to list objects, where are the object-name stored?
> 5.when a rbd file is put on erasure coded pool, where is the
> infomation(rbd name) of the rbd stored?
> 
> thanks
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

-- 
Loïc Dachary, Artisan Logiciel Libre


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