From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Elsayed Subject: Re: Erasure code library summary Date: Tue, 18 Jun 2013 18:10:17 -0700 Message-ID: References: <51C05123.8000002@dachary.org> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit Return-path: Received: from plane.gmane.org ([80.91.229.3]:48328 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932644Ab3FSBKf (ORCPT ); Tue, 18 Jun 2013 21:10:35 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1Up6ut-00063R-FQ for ceph-devel@vger.kernel.org; Wed, 19 Jun 2013 03:10:31 +0200 Received: from 66-87-113-27.pools.spcsdns.net ([66.87.113.27]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 19 Jun 2013 03:10:31 +0200 Received: from eternaleye by 66-87-113-27.pools.spcsdns.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 19 Jun 2013 03:10:31 +0200 Sender: ceph-devel-owner@vger.kernel.org List-ID: To: ceph-devel@vger.kernel.org Loic Dachary wrote: > Hi Ceph, > > Reed-Solomon coding family is the only one that can keep the chuncks > unencoded and therefore concatenable. In my understanding, this is not strictly true - any 'systematic' code will have the unencoded chunks remain available in this manner, and any non- systematic linear code can be transformed into a systematic code with the same minimum distance. Fountain codes are often explicitly constructed to maintain this property, as in the case of RaptorQ [RFC 6330]. https://en.wikipedia.org/wiki/Systematic_code