RE: CephFS + Erasure coding

From: Somnath Roy <Somnath.Roy@sandisk.com>
To: "Wang, Zhiqiang" <zhiqiang.wang@intel.com>,
	Gregory Farnum <greg@gregs42.com>
Cc: ceph-devel <ceph-devel@vger.kernel.org>
Subject: RE: CephFS + Erasure coding
Date: Wed, 6 May 2015 04:17:24 +0000	[thread overview]
Message-ID: <755F6B91B3BE364F9BCA11EA3F9E0C6F2CD86F6A@SACMBXIP01.sdcorp.global.sandisk.com> (raw)
In-Reply-To: <06E7D85B3BA36C4DB207FEDE871C53489D9E71@SHSMSX101.ccr.corp.intel.com>

Thanks Wang !
But, is this supported right now or coming with object stub implementation in Infernalis ?

Regards
Somnath

-----Original Message-----
From: Wang, Zhiqiang [mailto:zhiqiang.wang@intel.com] 
Sent: Tuesday, May 05, 2015 7:42 PM
To: Somnath Roy; Gregory Farnum
Cc: ceph-devel
Subject: RE: CephFS + Erasure coding

I think the readproxy mode is what you need. Read is proxied to the base tier, and write is on the cache tier.

-----Original Message-----
From: ceph-devel-owner@vger.kernel.org [mailto:ceph-devel-owner@vger.kernel.org] On Behalf Of Somnath Roy
Sent: Friday, May 1, 2015 5:58 AM
To: Gregory Farnum
Cc: ceph-devel
Subject: RE: CephFS + Erasure coding

Greg,
Probably not supported right now, but, wanted to confirm if there is any way we can use Ceph cache tier for only writes and reads are forwarded to the backend erasure coded pool.

Thanks & Regards
Somnath

-----Original Message-----
From: ceph-devel-owner@vger.kernel.org [mailto:ceph-devel-owner@vger.kernel.org] On Behalf Of Somnath Roy
Sent: Thursday, April 30, 2015 2:28 PM
To: Gregory Farnum
Cc: ceph-devel
Subject: RE: CephFS + Erasure coding

Got it , thanks !

-----Original Message-----
From: Gregory Farnum [mailto:greg@gregs42.com]
Sent: Thursday, April 30, 2015 2:21 PM
To: Somnath Roy
Cc: ceph-devel
Subject: Re: CephFS + Erasure coding

On Thu, Apr 30, 2015 at 1:55 PM, Somnath Roy <Somnath.Roy@sandisk.com> wrote:
> Hi Greg,
> Forgive my ignorance on this part if it is already discussed in the community. Could you please let me know if CephFS is supporting Erasure coded pool in the backend or not ?
> If not, is there any plan of supporting this kind of configuration in near future ?

You can set replicated cache pools, positioned as tiers over an EC pool, as data pools for CephFS. You cannot use EC pools directly for CephFS. We have no plans to add support for EC pools in the foreseeable future — since they have limited RADOS functionality we'd need to implement a whole log-structured file storage system or something. :( -Greg

>
> Thanks & Regards
> Somnath
>
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