From owner-freebsd-questions@FreeBSD.ORG Mon Nov 8 22:35:39 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9648F106566B for ; Mon, 8 Nov 2010 22:35:39 +0000 (UTC) (envelope-from rsmith@xs4all.nl) Received: from smtp-vbr12.xs4all.nl (smtp-vbr12.xs4all.nl [194.109.24.32]) by mx1.freebsd.org (Postfix) with ESMTP id 0B4D78FC13 for ; Mon, 8 Nov 2010 22:35:38 +0000 (UTC) Received: from slackbox.erewhon.net (slackbox.xs4all.nl [213.84.242.160]) by smtp-vbr12.xs4all.nl (8.13.8/8.13.8) with ESMTP id oA8MZVvo003045; Mon, 8 Nov 2010 23:35:31 +0100 (CET) (envelope-from rsmith@xs4all.nl) Received: by slackbox.erewhon.net (Postfix, from userid 1001) id 4DFE2B84D; Mon, 8 Nov 2010 23:35:31 +0100 (CET) Date: Mon, 8 Nov 2010 23:35:31 +0100 From: Roland Smith To: "C. P. Ghost" Message-ID: <20101108223531.GA54089@slackbox.erewhon.net> References: <20101106203016.GB13095@guilt.hydra> <20101106213836.GA77198@slackbox.erewhon.net> <4CD8194D.7080208@qeng-ho.org> <4CD82081.50309@stillbilde.net> <20101108183821.GA48373@slackbox.erewhon.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="h31gzZEtNLTqOjlF" Content-Disposition: inline In-Reply-To: X-GPG-Fingerprint: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 X-GPG-Key: http://www.xs4all.nl/~rsmith/pubkey.txt X-GPG-Notice: If this message is not signed, don't assume I sent it! User-Agent: Mutt/1.5.21 (2010-09-15) X-Virus-Scanned: by XS4ALL Virus Scanner Cc: "Svein Skogen \(Listmail account\)" , freebsd-questions@freebsd.org Subject: Re: ZFS License and Future X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Nov 2010 22:35:39 -0000 --h31gzZEtNLTqOjlF Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 08, 2010 at 09:44:29PM +0100, C. P. Ghost wrote: > On Mon, Nov 8, 2010 at 7:38 PM, Roland Smith wrote: > > On Mon, Nov 08, 2010 at 05:08:33PM +0100, Svein Skogen (Listmail accoun= t) wrote: > >> But it's still not capable of true forward-error-correction. If we are > >> to embark upon creating a new solution, using something that is cheap > >> for "normal cases" but can still be used (albeit more expensively) for > >> error recovery would (imho) be better. Even if that means we get less > >> net storage out of the gross pool (it could perhaps be configurable?) > > > > I'm not sure what you mean by "true forward-error-correction". But if y= ou want > > to make _really sure_ that a spinning disk hasn't mangled the data you = should: >=20 > Maybe something like Reed-Solomon ECC in different blocks. > Should a data block go bad, it could be rebuilt on-the-fly from > those ECC blocks: And how do you detect that a block has gone bad, other than reading back wh= at you wrote and finding a difference? Because that would still be slow. Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --h31gzZEtNLTqOjlF Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (FreeBSD) iEYEARECAAYFAkzYezMACgkQEnfvsMMhpyUyWwCgnybbD+Jm3ZvZch16XpdjS/Xq txcAoJgYykBKLkeehGKpyDP5UB7WcSk6 =OZHT -----END PGP SIGNATURE----- --h31gzZEtNLTqOjlF--