ZFS License and Future

krad kraduk at gmail.com
Mon Nov 8 22:44:19 UTC 2010

On 8 November 2010 22:35, Roland Smith <rsmith at xs4all.nl> wrote:

> 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 at xs4all.nl> wrote:
> > > On Mon, Nov 08, 2010 at 05:08:33PM +0100, Svein Skogen (Listmail
> account) 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
> you want
> > > to make _really sure_ that a spinning disk hasn't mangled the data you
> should:
> >
> > 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
> what
> you wrote and finding a difference? Because that would still be slow.
> Roland
> -y
> R.F.Smith                                   http://www.xs4all.nl/~rsmith/<http://www.xs4all.nl/%7Ersmith/>
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The read doesnt need to be done at write time, it only needs to be done when
the block is read by the system. If an issue is found than the corrective
measures are executed. For you important data in my opinion you should
always set the copies attribute to 3. This is obviously very costly in terms
of storage but its just a trade off for the data.

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