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 22:19:45 2014
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Date: Sun, 07 Dec 2014 03:20:22 +0000
From: Ruben Safir
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Subject: Re: [LIU Comp Sci] Parity Bit Algebra
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Nuh?
So post and give me credits in your HW assignment since I gave you the
key to the solution 3 days ago
Ruben
On 12/07/2014 03:02 AM, Maneesh Kongara wrote:
> Damn! I get it now!!!
> On Dec 6, 2014 10:00 PM, "Maneesh Kongara" wrote:
>
>> It gives us the desired answer?
>> On Dec 6, 2014 9:58 PM, "Ruben Safir" wrote:
>>
>>> 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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