ZFS License and Future

Arthur Chance freebsd at qeng-ho.org
Mon Nov 8 15:37:51 UTC 2010

On 11/08/10 13:52, krad wrote:
> On 6 November 2010 21:38, Roland Smith<rsmith at 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 extra
>>>> features of zfs. Personally I cant see how anyone with any important
>> 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
>> --
>> R.F.Smith                                   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 the
> checksum doesnt match etc?

Good point. Geli uses a crypto standard hash (HMAC/SHA256 is 
recommended) as it's all about authentication in the face of potentially 
malicious attack, and that's fairly expensive. ZFS by default uses the 
fletcher2 (= fletcher32) hash, which is simple and fast, as it's used to 
make sure that hardware hasn't accidentally mangled your data.

"Although the wombat is real and the dragon is not, few know what a
wombat looks like, but everyone knows what a dragon looks like."

	-- Avram Davidson, _Adventures in Unhistory_

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