MESSAGE
| DATE | 2014-12-06 |
| FROM | Ruben Safir
|
| SUBJECT | Re: [LIU Comp Sci] Parity Bit Algebra
|
From owner-learn-outgoing-at-mrbrklyn.com Sat Dec 6 21:58:43 2014
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Date: Sun, 07 Dec 2014 02:59:19 +0000
From: Ruben Safir
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Subject: Re: [LIU Comp Sci] Parity Bit Algebra
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On 12/07/2014 02:50 AM, Maneesh Kongara wrote:
> Have you seen the review questions?
What happens when you subtract a comp 2 number again and again
>
> On Sat, Dec 6, 2014, 9:49 PM Ruben Safir wrote:
>
>>
>> I can't even read the question
>>
>>
>>
>> On 12/07/2014 02:38 AM, Maneesh Kongara wrote:
>>> I've finished all other questions... I'm breaking my head with the last
>>> question.
>>> On Dec 6, 2014 9:36 PM, "Ruben Safir" wrote:
>>>
>>>> On 12/06/2014 11:09 PM, Maneesh Kongara wrote:
>>>>> Preliminary work as in answers to the other questions of the
>> assignment?
>>>>> On Dec 6, 2014 6:08 PM, "Ruben Safir" wrote:
>>>> I'm going to crash, how far did you get in the assingment.
>>>>
>>>> Call me is 20 minutes. I have one hour to do it :)
>>>>
>>>>
>>>>>> On 12/06/2014 10:52 PM, Maneesh Kongara wrote:
>>>>>>> Thanks so much for sharing Mr Rubin. Have you completed the
>> assignment?
>>>>>>> On Dec 6, 2014 5:49 PM, "Ruben Safir" wrote:
>>>>>> Not even looked at it outside of the library. I'm burning up trying
>> to
>>>>>> catch up. Do you have some preliminary work?
>>>>>>
>>>>>> I did give it throught. Part of the solution must have to do with the
>>>>>> Comp + 2 binary
>>>>>>
>>>>>> I can't even find my notes...
>>>>>>
>>>>>>>> This is from theidiscussion of Raid 3 Stallings Text which the slide
>>>>>>>> come from. It is related to the problem you asked about the parity
>>>> bit
>>>>>>>> calculation for the Hamming Code
>>>>>>>>
>>>>>>>> Not the methodology for logical calculation, it is straight math
>>>>>>>>
>>>>>>>> Note that X is XOR for whatever UFT reason
>>>>>>>>
>>>>>>>>
>>>>>>>> REDUNDANCY In the event of a drive failure, the parity drive is
>>>> accessed
>>>>>>>> and data is reconstructed from the remaining devices. Once the
>> failed
>>>>>>>> drive is replaced, the missing data can be restored on the new drive
>>>> and
>>>>>>>> operation resumed.
>>>>>>>>
>>>>>>>> Data reconstruction is simple. Consider an array of five drives in
>>>> which
>>>>>>>> X0 through X3 contain data and X4 is the parity disk.The parity for
>>>> the
>>>>>>>> ith bit is calculated as follows:
>>>>>>>>
>>>>>>>> X4(i) = X3(i) { X2(i) { X1(i) { X0(i)
>>>>>>>>
>>>>>>>> where { is exclusive-OR function.
>>>>>>>>
>>>>>>>> Suppose that drive X1 has failed. If we add X4(i) { X1(i) to both
>>>> sides
>>>>>>>> of the preceding equation, we get
>>>>>>>>
>>>>>>>> X1(i) = X4(i) { X3(i) { X2(i) { X0(i)
>>>>>>>>
>>>>>>>>
>>>>>>>> file:///home/ruben/william stallings - computer organization and
>>>>>>>> architecture designing for performance (8th edition).pdf
>>>>>>>>
>>>>>>>> Page 202
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> http://www.nylxs.com/images/raid3_parity_math.png
>>>>>>>>
>>>>>>>> Ruben
>>>>>>>>
>>
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