Date: Mon, 08 Nov 2010 17:08:33 +0100 From: "Svein Skogen (Listmail account)" <svein-listmail@stillbilde.net> To: freebsd-questions@freebsd.org Subject: Re: ZFS License and Future Message-ID: <4CD82081.50309@stillbilde.net> In-Reply-To: <4CD8194D.7080208@qeng-ho.org> 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>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig0B15181B9B731332876079AC Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 08.11.2010 16:37, Arthur Chance wrote: > On 11/08/10 13:52, krad wrote: >> On 6 November 2010 21:38, Roland Smith<rsmith@xs4all.nl> wrote: >> >>> On Sat, Nov 06, 2010 at 02:30:16PM -0600, Chad Perrin wrote: >>>>> Having said all that it really depends on whether you need the extr= a >>>>> features of zfs. Personally I cant see how anyone with any importan= t >>> data >>>>> can do without checksuming. >>>> >>>> I guess that depends on what you're doing with the data and what >>>> kind of >>>> external tools you have in place to protect/duplicate it in case of = a >>>> problem. >>> >>> The GEOM_ELI class provides optional authentication/checksumming. See= >>> geli(8), >>> especially the -a option. >>> >>> Roland >>> --=20 >>> R.F.Smith =20 >>> http://www.xs4all.nl/~rsmith/<http://www.xs4all.nl/%7Ersmith/>; >>> [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much >>> appreciated] >>> pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: >>> C321A725) >>> >> >> im not sure on whether that you be a viable replacement, as it has to >> be a >> fairly good checksum to avoid clashes, whilst also being quick so it >> doesnt >> adversly affect disk performance. Also what does it do if it detects t= he >> checksum doesnt match etc? >=20 > Good point. Geli uses a crypto standard hash (HMAC/SHA256 is > recommended) as it's all about authentication in the face of potentiall= y > malicious attack, and that's fairly expensive. ZFS by default uses the > fletcher2 (=3D fletcher32) hash, which is simple and fast, as it's used= to > make sure that hardware hasn't accidentally mangled your data. 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?) //Svein --=20 --------+-------------------+------------------------------- /"\ |Svein Skogen | svein@d80.iso100.no \ / |Solberg =D8stli 9 | PGP Key: 0xE5E76831 X |2020 Skedsmokorset | svein@jernhuset.no / \ |Norway | PGP Key: 0xCE96CE13 | | svein@stillbilde.net ascii | | PGP Key: 0x58CD33B6 ribbon |System Admin | svein-listmail@stillbilde.net Campaign|stillbilde.net | PGP Key: 0x22D494A4 +-------------------+------------------------------- |msn messenger: | Mobile Phone: +47 907 03 575 |svein@jernhuset.no | RIPE handle: SS16503-RIPE --------+-------------------+------------------------------- A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail? ------------------------------------------------------------ Picture Gallery: https://gallery.stillbilde.net/v/svein/ ------------------------------------------------------------ --------------enig0B15181B9B731332876079AC Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.14 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkzYIIQACgkQODUnwSLUlKSAXACeMlNzhpV76oIQh69FODfk/YR3 o5kAoKRgLRU2Skx72G515Iop9GpIc02K =KqNS -----END PGP SIGNATURE----- --------------enig0B15181B9B731332876079AC--
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