Ik zag bij een geheugenreepje met of zonder ECC te koop. Wat is ECC en waarom is het duurder ...
Ik wordt een beetje moe, ik heb deze vraag de afgelopen weken al een stuk of 4 keer behandeld.
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ECC = Error Correction Code
Heb je niet nodig. Meeste mobos ondersteunen het niet eens.
Alleen bij Compraqs verplicht (vaak).
ECC is alleen nuttig bij "mission-critical" servers...
Heb je niet nodig. Meeste mobos ondersteunen het niet eens.
Alleen bij Compraqs verplicht (vaak).
ECC is alleen nuttig bij "mission-critical" servers...
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Inderdaad te vaak geposted!Op maandag 22 januari 2001 09:35 schreef GarBaGe het volgende:
ECC = Error Correction Code
Heb je niet nodig. Meeste mobos ondersteunen het niet eens.
Alleen bij Compraqs verplicht (vaak).
ECC is alleen nuttig bij "mission-critical" servers...
Jammer dat er dan ook verkeerde antwoorden op gegeven worden
ECC is namelijk : Error Checking and Correcting.
Zeker niet alleen in Compaqs!
Hiero nog wat meer info voor allen:
"What is ECC?
ECC is an acronym for Error Checking and Correcting. ECC is used in several
areas of computer operations, but the focus of this paper is on ECC in main
memory.
ECC is similar to parity. However, where parity can only detect errors, ECC
can actually correct most errors. By correcting memory errors, mission
critical computer operations can continue.
What kinds of errors occur in RAM?
In order of likelihood, the most common memory errors are: Single-Bit,
Multi-Bit, Column, and Row. Single-bit errors are the most common and are
characterized by a single bit of data being incorrect when reading a
complete byte or word. A multi-bit error is the result of more than one bit
being erroneous within the same byte or word. A single column or row error
would appear as single-bit errors in multiple words.
How are these error corrected?
ECC memory uses extra bits to store an encrypted code with the data. When
the data is written to memory, the ECC code is simultaneously stored. Upon
being read back, the stored ECC code is compared to the ECC code generated
when the data was read. If the codes don't match, they are decrypted to
determine which bit in the data is incorrect. The erroneous bit is "flipped"
and the memory controller releases the corrected data.
Errors are corrected "on-the-fly," and corrected data is rarely placed back
in memory. If the same corrupt data is read again, the correction process is
repeated. Replacing the data in memory would require processing overhead
that could accumulate and significantly diminish system performance. If the
error occurred because of random events and isn't a defect in the memory,
the memory address will be cleaned of the error when the data is overwritten
with other data.
How many extra bits are required for ECC?
By encrypting the ECC code and correcting only single bit errors, very few
additional bits are required. Unlike parity, the number of ECC bits doesn't
increase at the same rate as the bits per word or data bandwidth. As word
size doubles, parity bits double, but ECC bits increase by one. So, if a
system uses an 8 bit word, it would need 1 bit for parity checking, but 5
bits for ECC. However, a 32 bit word needs 4 bits for parity or 7 bits for
ECC. Increase the bandwidth to 64 bits and 8 bits are required for both
parity or ECC. Below is a chart comparing the bits required for different
data bandwidths for ECC and parity:
Word Bits ECC Bits Parity Bits
8 5 1
16 6 2
32 7 4
64 8 8
128 9 16
So what?
As you can see, at the 64 bit level, it is equally efficient to use ECC or
parity. This is how manufacturers use 36 bit memory modules in groups of 2
or more to create an ECC environment. Compaq's Tri-Flex memory bus is such a
system. The Tri-Flex bus uses 4 SIMM groups, for a 128 bit bandwidth. Since
the 4 modules have 16 spare bits between them, the 9 bits needed for ECC are
easily satisfied. Other systems may use special ECC memory modules, but the
cost benefit and availability of industry standard 36 bit SIMMs appeals to
designers and end-users.
How is ECC used in the real world?
Systems that use ECC, may use it differently. Usually, when data requires
correction, the operating system logs the error and reports the error to the
system administrator. Multiple errors may be reported for the same memory
location, if the data is read more than once without being replaced by
different data. If the same memory location is corrected after a system
powerdown, a defect is most likely present in the memory and should be
replaced."
Hmmz ...
Ik heb hier nog een servertje staan waar ECC SIMMs in moeten .. iemand enig id waar dat nog te koop is ?
ThX
Koffie
Ik heb hier nog een servertje staan waar ECC SIMMs in moeten .. iemand enig id waar dat nog te koop is ?
ThX
Koffie
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PRicewatch?Op maandag 22 januari 2001 10:18 schreef Koffie het volgende:
Hmmz ...
Ik heb hier nog een servertje staan waar ECC SIMMs in moeten .. iemand enig id waar dat nog te koop is ?
ThX
Koffie
Verkopen ze vrij veel...
Ja, en er zijn nog wel mensen die willen reageren, als je het niet wilt, dan moet je niet zeiken, en niet reageren!!!!!!Op maandag 22 januari 2001 09:29 schreef mvdejong het volgende:
Ik wordt een beetje moe, ik heb deze vraag de afgelopen weken al een stuk of 4 keer behandeld.
Probeer eens de zoek-functie van de forums.
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