Date: Sat, 28 Jun 2008 09:56:13 -0700 From: prad <prad@towardsfreedom.com> To: freebsd-questions@freebsd.org Subject: Re: first pre-emptive raid Message-ID: <20080628095613.38e92182@gom.home> In-Reply-To: <200806281302.20814.pieter@degoeje.nl> References: <20080628005702.2137bb8c@gom.home> <200806281302.20814.pieter@degoeje.nl>
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On Sat, 28 Jun 2008 13:02:20 +0200
Pieter de Goeje <pieter@degoeje.nl> wrote:
> Parity is calculated using the following formula:
>
pieter, that is absolutely beautiful!!
it was really bothering me how you can recover data that really wasn't
'there'.
my son and i just worked out the mechanism with some nibbles:
0110 d0
0011 d1
0010 d2
====
0111 p
so
0111 p 0111 p 0111 p
0011 d1 0110 d0 0110 d0
0010 d2 0010 d2 0011 d1
==== ==== ====
0110 d0 0011 d1 0010 d2
and just extend the concept from nibbles to blocks.
why in diagram 20-3 of the handbook do they show 2 parity blocks though
for disk3 and disk4? why would you ever have more than 1 for any single
disk?
--
In friendship,
prad
... with you on your journey
Towards Freedom
http://www.towardsfreedom.com (website)
Information, Inspiration, Imagination - truly a site for soaring I's
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