From mboxrd@z Thu Jan 1 00:00:00 1970 From: Loic Dachary Subject: Re: Locally Repairable Codes vs Pyramid Date: Thu, 05 Jun 2014 16:00:50 +0200 Message-ID: <53907812.6030100@dachary.org> References: <538C9FA2.3020805@dachary.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="3gr566B5Ep0hKbeN13E6ob7GiuGjVvtxr" Return-path: Received: from smtp.dmail.dachary.org ([91.121.254.229]:34797 "EHLO smtp.dmail.dachary.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751664AbaFEOAx (ORCPT ); Thu, 5 Jun 2014 10:00:53 -0400 Received: from [10.9.0.6] (unknown [10.0.2.28]) by smtp.dmail.dachary.org (Postfix) with ESMTP id D69E1428A3 for ; Thu, 5 Jun 2014 16:00:50 +0200 (CEST) In-Reply-To: <538C9FA2.3020805@dachary.org> Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Ceph Development This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --3gr566B5Ep0hKbeN13E6ob7GiuGjVvtxr Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable For the record and since nobody objected, I made the suggested change. On 02/06/2014 18:00, Loic Dachary wrote: > Hi Ceph, >=20 > TL;DR: s/pyramid/LRC/ in the implementation of http://pad.ceph.com/p/cd= sgiant-pyramid-erasure-code for clarity >=20 > Although the term "Pyramid code" has been consistently used in referenc= e to the technique used to reduce the network requirements when repairing= from the loss of a single OSD (put simply ;-), I realized today when dis= cussing with Dan Lambright and Xavier Hernandez from glusterfs that I was= unclear about what it really means. >=20 > As far as I can tell, LRC as described in http://anrg.usc.edu/~maheswar= an/Xorbas.pdf suggests an implementation that is close to what has been d= escribed during the last CDS. In contrast the pyramid code paper http://r= esearch.microsoft.com/pubs/70415/tr-2007-25.pdf suggests a more sophistic= ated approach which I do not fully understand.=20 >=20 > Instead of hardcoding the word "pyramid" in the pathnames of the implem= entation it seems better to use "LRC" instead. >=20 > Cheers >=20 --=20 Lo=EFc Dachary, Artisan Logiciel Libre --3gr566B5Ep0hKbeN13E6ob7GiuGjVvtxr Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlOQeBIACgkQ8dLMyEl6F23gAwCfWqsa2H4ZF+o6Bs/1PjYp4dcC L5sAnRclLl8mV5A8aO7aDqjRTWOm7a41 =ioa0 -----END PGP SIGNATURE----- --3gr566B5Ep0hKbeN13E6ob7GiuGjVvtxr--