Date: Mon, 8 Nov 2010 23:35:31 +0100 From: Roland Smith <rsmith@xs4all.nl> To: "C. P. Ghost" <cpghost@cordula.ws> Cc: "Svein Skogen \(Listmail account\)" <svein-listmail@stillbilde.net>, freebsd-questions@freebsd.org Subject: Re: ZFS License and Future Message-ID: <20101108223531.GA54089@slackbox.erewhon.net> In-Reply-To: <AANLkTikcCFr4GttjNrq9Kxxz1pyZbPc82BsJ6a3siw5t@mail.gmail.com> References: <AANLkTi=dKatHYLFhC35VTT4fCAKgYLKEri2yVCPtSv7g@mail.gmail.com> <AANLkTinxLcrRoB6b2AcTrxHLqRCkyoWUhU=EmuvzEZQ8@mail.gmail.com> <20101106203016.GB13095@guilt.hydra> <20101106213836.GA77198@slackbox.erewhon.net> <AANLkTi=7MhvRTLP1NzGaHQFsV=FU8QDn5K73EmLPZH2k@mail.gmail.com> <4CD8194D.7080208@qeng-ho.org> <4CD82081.50309@stillbilde.net> <20101108183821.GA48373@slackbox.erewhon.net> <AANLkTikcCFr4GttjNrq9Kxxz1pyZbPc82BsJ6a3siw5t@mail.gmail.com>
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--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 <rsmith@xs4all.nl> 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--
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