Re: Is this enough for us to have triple-parity RAID?

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On Thu, Apr 26, 2012 at 12:59 AM, Emmanuel Noobadmin
<centos.admin@xxxxxxxxx> wrote:
> On 4/25/12, Alex <creamyfish@xxxxxxxxx> wrote:
>> I can see that you are trying very hard to fit a new picture into an old
>> frame. But with new technology there is always new possibilities. For
>> example, what I am thinking is: with the new laser write head, it doesn't
>> necessarily require the head to stay very close  to the platter since laser
>> doesn't fade away with longer distance, which may enable a design that
>
> The strength of the laser will fall as the distance to the media
> increases, wouldn't it?
>
>> the head turns(the platter doesn't have to be round) instead of spinning
>>  the platter; hence the "Data rate is a product of [density * RPM]"
>> statement falls apart. What is more, if the cost is justified, one may
>> even design a disk with multiple write heads to increase the bandwidth
>> since now we are free from the fluid mechanic interaction between the
>> head and the platter. Both of these may lead to independent increase
>> of data rate. I am having these thoughts because it's been an endless
>
> But Ostler's technique only increases the write speed and admits in a
> Wired.com article there is still no faster/other way to read the data.
> So we would still be stuck with the rotating disk and the magnetic
> reading heads until some other breakthrough happens.
>
> Going back into the context of parity RAID rebuild, we would still be
> bottlenecked on the write side wouldn't we since bits on the
> replacement drive can only be calculated after reading the rest of the
> drives.

I also want to add that sluggishness of read operations can always be
alleviated by prefetching and masked by the speed of a cache.

Cheers,
Alex
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