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List:       ceph-users
Subject:    [ceph-users] LRC low level plugin configuration can't express maximal erasure resilience
From:       loic () dachary ! org (Loic Dachary)
Date:       2017-04-29 20:58:08
Message-ID: 5d82ecfc-2ddf-e3e2-cf25-6447943d6405 () dachary ! org
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Hi Matan,

On 04/29/2017 10:47 PM, Matan Liram wrote:
> LRC low level plugin configuration of the following example copes with a single \
> erasure while it can easily protect from two. 
> In case I use the layers:
> 1: DDDDDDc_ _
> 2: DDD_ _ _ _c_
> 3: _ _ _DDD_ _c
> 
> Neither of the rules protect from 2 failures. However, if we calculate the XOR of \
> the two local parities we can treat the calculated value as a second parity disk \
> and cope with two erasures. This thread discusses the same issue, while according \
> to my understanding it doesn't provide a solution. \
> http://www.spinics.net/lists/ceph-devel/msg19886.html 
> Is there a way to make the proposed construction cope with 2 erasures? A few \
> modifications are acceptable.

I'm not sure to understand what you're asking. Would you mind rephrasing ?

1: DDDDDDc_ _
2: DDD_ _ _ _c_
3: _ _ _DDD_ _c


1: DDDDDDc_ __
2: DDD_ _ _ _c__
3: _ _ _DDD_ _cc

That would not work ?

Cheers

> 
> Thank you,
> Matan Liram
> 
> 
> 
> 
> _______________________________________________
> ceph-users mailing list
> ceph-users at lists.ceph.com
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> 

-- 
Lo?c Dachary, Artisan Logiciel Libre


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