[ILUG] Why RAID
paul at clubi.ie
Thu Jul 15 12:22:40 IST 2004
On Thu, 15 Jul 2004, Colm Buckley wrote:
> When you add the new (C) drive, all of its data are zeroes, which
> doesn't change the parity data (N XOR 0 = N). Fiendishly clever.
Hmm, surely you'd have to zero the new disk first though? I dont
think you can rely on a new disk being all zero. ;)
Also, it doesnt matter, you have to know which the new block is to be
able to read the stripe correctly surely? (otherwise data of xy turns
into xy(0)). If you know that, you can also ignore that new block
when calculting the parity, and hence you dont need to need to care
what value the new block is.
Paul Jakma paul at clubi.ie paul at jakma.org Key ID: 64A2FF6A
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