ZFS License and Future

[Arthur Chance]

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/>
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>>
>
> 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.

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