From mboxrd@z Thu Jan 1 00:00:00 1970 From: Loic Dachary Subject: Re: erasure pool with isa plugin Date: Tue, 23 Jun 2015 06:15:03 -0400 Message-ID: <558931A7.9040501@dachary.org> References: <55887F63.1000404@dachary.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="WSTkoOO1Puo1opX5Nn1SA7jF0tFso7McN" Return-path: Received: from mail2.dachary.org ([91.121.57.175]:38668 "EHLO smtp.dmail.dachary.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751055AbbFWKPG (ORCPT ); Tue, 23 Jun 2015 06:15:06 -0400 In-Reply-To: Sender: ceph-devel-owner@vger.kernel.org List-ID: To: Gregory Farnum Cc: "Deneau, Tom" , ceph-devel This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --WSTkoOO1Puo1opX5Nn1SA7jF0tFso7McN Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hi, On 23/06/2015 06:06, Gregory Farnum wrote: > On Mon, Jun 22, 2015 at 10:34 PM, Loic Dachary wrote= : >> Hi Tom, >> >> On 22/06/2015 17:10, Deneau, Tom wrote: >>> If one has a cluster with some nodes that can run with the ISA plugin= >>> and some that cannot, is there a way to define a pool such that the >>> ISA-capable nodes can use the ISA plugin and the others can use say >>> the jerasure plugin? >> >> There is no way to do that, because there is no guarantee that an obje= ct encoded by jerasure can be decoded by isa and vice versa. >=20 > Shouldn't we be able to set up something that *does* guarantee that, > though? Either by combining them into a single plugin which > dynamically configures to the fastest possible for that machine, or by > running them against the same object corpus and requiring that they > produce the same output? I don't know enough about the maths involved to evaluate how difficult it= is. Although both implement Reed Solomon using Vandermonde or Cauchy mat= rices, I think there are details that makes the output different.=20 Cheers > -Greg >=20 --=20 Lo=C3=AFc Dachary, Artisan Logiciel Libre --WSTkoOO1Puo1opX5Nn1SA7jF0tFso7McN 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) iEYEARECAAYFAlWJMacACgkQ8dLMyEl6F2252ACfWBaGtMlC1Fam+I73ouVZHCCw qZIAoKOBA+f/PKFP29EfSlKQnCr/hraQ =pyKS -----END PGP SIGNATURE----- --WSTkoOO1Puo1opX5Nn1SA7jF0tFso7McN--