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Questions about DDR RAM



 
 
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  #41  
Old October 6th 07, 11:03 PM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
krw
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Posts: 402
Default Questions about DDR RAM

In article ,
says...
On 2007-10-03 kony wrote:
On Wed, 03 Oct 2007 16:30:41 -0000, Andrew
wrote:

Memory is fairly reliable provided you aren't recklessly overclocking
things so I'd consider ECC inappropriate on all but the most mission-
critical systems. Unless you are talking about a machine already
fitted out with a UPS, hot-swappable RAID, redundant power supplies
and preferably an secure, climate controlled machine room to put it
all in there are more important risk factors to consider.


None of those risk factors change whether the results of
data calculations are important.

I would say ECC is appropriate for any even slightly
critical application, not just "the most mission critical".
You spend a few bucks more for better PSU, case, processor,
etc, why not the memory? Your data links usually have error
correction, as does a hard drive internally, as does the
processor cache, but main memory is a weak link in data
integrity.


Well, some of these factors _can_ affect calculations in the same
manner as bad memory - e.g. anything can happen with a brief power
outage that a regular PSU can _just_about_ bridge, including
incorrect calculations in the CPU, bad data on the bus lines or
whatever. However, I'm not questioning the fact that ECC is
extremely useful and yes, and aid to reliability. What I am
questioning is whether it should be regarded as a priority.


Priority? NO, but for an 11% uplift over *CHEAP* DRAM, it's
surprising it's not standard again. I have ECC memory on my
"desktop" (at a cost *way* over 111%) and would have bought it for my
laptop, if it were available. Bit-rot is a PITA.

How often do you see bad hard drives, or blown PSUs, or have a
machine cut out in a power cut? These are a computer's weak points
so it makes sense to protect them. It's a little more difficult
to diagnose memory errors in a non-ECC PC because they would usually
appear to be much-more-likely software problems.


Right. Just because you can blame it on M$ doesn't mean it is. It
is *nice* to know when a component is failing. As you point out,
it's extremely difficult to diagnose memory problems. ECC/Parity
would make it far simpler.

However, look at a machine equipped with ECC memory. How often do
you see memory errors logged? Approximately never. Cast your mind
back ten or twelve years when even commodity machines had parity
memory. How often did you see the BIOS message saying it had frozen
the system because of a parity error? I only ever saw it once.
While my memory is vague ISTR that I discounted it at the time as
it was from a system with other hardware problems. Ask yourself
why parity was removed from memory. Yes, it did save money but
why did the computer industry en masse decide that it could safely
be dispensed with?


I see them on my "desktop" system. I've come to the conclusion that
they're ghosts cause by a BIOS problem, but they're there.

In short ECC will improve a system's reliability, but not by much.
You are far better off spending the money elsewhere, looking at
more likely causes of failiure, and considering backup, redundancy
etc first. Only when those have been covered is it worth worrying
over whether your machine has ECC memory or not.


It's a cheap thing to do to catch a difficult problem to diagnose.
If you've ever suffered a severe case of bit-rot I'm sure you would
be a little more sensitive to sources of errors.

--
Keith
  #42  
Old October 7th 07, 10:50 PM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
Franc Zabkar
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Posts: 1,118
Default Questions about DDR RAM

On Wed, 03 Oct 2007 16:30:41 -0000, Andrew
put finger to keyboard and composed:

On 3 Oct, 08:55, Igor wrote:
However, I plan on putting together a PC from scratch in the near future,
so perhaps ECC support is something I should be looking for in a
motherboard.

In a nutshell, why is ECC capable memory more desirable?


It has additional bits used to store checksum information so that
errors can be detected and simple ones corrected. In short, it's a
reliability thing. Without knowing much about your set up, it's
impossible to be sure but at three or four times the cost of normal
RAM I doubt it will be a cost-effective way of improving
reliability.


ECC just adds one extra RAM, ie 9 chips versus 8, or 72 bits versus
64. Even allowing for economies of scale, I can't see why you would
expect a 3x or 4x price difference.

Kingston 1GB 333MHz DDR ECC Registered CL2.5 DIMM Dual Rank, x8
(US$70):
http://www.ec.kingston.com/ecom/conf...R333D8R2 5/1G

Kingston 1GB 333MHz DDR Non-ECC CL2.5 DIMM (US$54):
http://www.ec.kingston.com/ecom/conf...333X64C 25/1G

If you want to do that on most systems, you're better
off spending the money on things like fitting a UPS and RAID storage -
these cover much less reliable elements of the system.

Memory is fairly reliable provided you aren't recklessly overclocking
things so I'd consider ECC inappropriate on all but the most mission-
critical systems. Unless you are talking about a machine already
fitted out with a UPS, hot-swappable RAID, redundant power supplies
and preferably an secure, climate controlled machine room to put it
all in there are more important risk factors to consider.


- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
  #43  
Old October 8th 07, 03:54 AM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
Del Cecchi
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Posts: 84
Default Questions about DDR RAM


"kony" wrote in message
...
On Fri, 5 Oct 2007 15:17:57 +0000 (UTC), Andrew Smallshaw
wrote:

Yes, it did save money but
why did the computer industry en masse decide that it could safely
be dispensed with?


Because they don't particularly care if a customer's
calculations/etc end up wrong if it's not guaranteed for
some critical use. The industry didn't actually abandon it
for critical uses.


In fact, for critical usage some companies have gone far beyond normal
SEC/DED error correction in servers.
I suppose I ought to trim the crossposting...


  #44  
Old October 8th 07, 04:20 AM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
daytripper
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Posts: 265
Default Questions about DDR RAM

On Sun, 7 Oct 2007 21:54:21 -0500, "Del Cecchi"
wrote:


"kony" wrote in message
.. .
On Fri, 5 Oct 2007 15:17:57 +0000 (UTC), Andrew Smallshaw
wrote:

Yes, it did save money but why did the computer industry en masse decide
that it could safely be dispensed with?


Because they don't particularly care if a customer's
calculations/etc end up wrong if it's not guaranteed for
some critical use. The industry didn't actually abandon it
for critical uses.


In fact, for critical usage some companies have gone far beyond normal
SEC/DED error correction in servers.


If you are referring to ECC schemes and not memory mirroring, I'd be
interested in examples that *don't* simply use n Hamming codewords to turn
n-bit-wide full chip failures into correctable events - which really wasn't
that remarkable, revolutionary or heroic when it was first employed - about 20
years ago...

I suppose I ought to trim the crossposting...


And what fun would that be?

/daytripper ;-)
  #45  
Old October 8th 07, 04:52 AM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
Frank McCoy
external usenet poster
 
Posts: 704
Default Questions about DDR RAM

In alt.comp.hardware.pc-homebuilt daytripper
wrote:

On Sun, 7 Oct 2007 21:54:21 -0500, "Del Cecchi"
wrote:


"kony" wrote in message
. ..
On Fri, 5 Oct 2007 15:17:57 +0000 (UTC), Andrew Smallshaw
wrote:

Yes, it did save money but why did the computer industry en masse decide
that it could safely be dispensed with?

Because they don't particularly care if a customer's
calculations/etc end up wrong if it's not guaranteed for
some critical use. The industry didn't actually abandon it
for critical uses.


In fact, for critical usage some companies have gone far beyond normal
SEC/DED error correction in servers.


If you are referring to ECC schemes and not memory mirroring, I'd be
interested in examples that *don't* simply use n Hamming codewords to turn
n-bit-wide full chip failures into correctable events - which really wasn't
that remarkable, revolutionary or heroic when it was first employed - about 20
years ago...

It's just a hamming-code.
However, about 99% of memory installed on PCs is *not* EEC or even
parity enabled. They all *should* be.

I suppose I ought to trim the crossposting...


And what fun would that be?

/daytripper ;-)


--
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(_/ / (_(_/|_/ / _/ _
  #46  
Old October 8th 07, 03:11 PM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
Del Cecchi
external usenet poster
 
Posts: 84
Default Questions about DDR RAM


"daytripper" wrote in message
...
On Sun, 7 Oct 2007 21:54:21 -0500, "Del Cecchi"
wrote:


"kony" wrote in message
. ..
On Fri, 5 Oct 2007 15:17:57 +0000 (UTC), Andrew Smallshaw
wrote:

Yes, it did save money but why did the computer industry en masse
decide
that it could safely be dispensed with?

Because they don't particularly care if a customer's
calculations/etc end up wrong if it's not guaranteed for
some critical use. The industry didn't actually abandon it
for critical uses.


In fact, for critical usage some companies have gone far beyond normal
SEC/DED error correction in servers.


If you are referring to ECC schemes and not memory mirroring, I'd be
interested in examples that *don't* simply use n Hamming codewords to
turn
n-bit-wide full chip failures into correctable events - which really
wasn't
that remarkable, revolutionary or heroic when it was first employed -
about 20
years ago...

I suppose I ought to trim the crossposting...


And what fun would that be?

/daytripper ;-)


In some sense it is a hamming code or along those lines. but it includes
redundant bit steering, correction of double errors when one is hard and
the other soft, package codes, scrubbing, etc. The whole quote was "far
beyond normal SEC/DED...." eg 64/72 type codes that do single bit
correction and double bit detection.

del


  #47  
Old October 8th 07, 07:48 PM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
Robert Redelmeier
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Posts: 316
Default Questions about DDR RAM

In comp.sys.ibm.pc.hardware.chips Frank McCoy wrote in part:
However, about 99% of memory installed on PCs is *not*
EEC or even parity enabled. They all *should* be.


Oh, pray tell, why? Do you believe you know the PC
business better than Intel, AMD, Dell, HP, ... who have
decided to manufacture chipsets and computers without ECC?

Do you believe ~50 US$/box is better spent on ECC than on
improved capacitors, mobo layers, cabling, cooling or shielding?

There are always many improvements possible. The key is to
choose the best ones. Not fixate like a kid in a candy store.

-- Robert

  #48  
Old October 8th 07, 08:34 PM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
Frank McCoy
external usenet poster
 
Posts: 704
Default Questions about DDR RAM

In alt.comp.hardware.pc-homebuilt Robert Redelmeier
wrote:

In comp.sys.ibm.pc.hardware.chips Frank McCoy wrote in part:
However, about 99% of memory installed on PCs is *not*
EEC or even parity enabled. They all *should* be.


Oh, pray tell, why? Do you believe you know the PC
business better than Intel, AMD, Dell, HP, ... who have
decided to manufacture chipsets and computers without ECC?

Do you believe ~50 US$/box is better spent on ECC than on
improved capacitors, mobo layers, cabling, cooling or shielding?

It shouldn't add more than 10% to the price of memory; which would be
about 2% or less of the price of the computer itself.

The problem isn't Intel or anybody else with the possible exception of
IBM; but there only slightly.

The problem is custom and history.
They didn't do it in the past, for fairly good and decent reasons.
They don't do it *now* because they didn't do it in the past.
That is NOT a good reason.

There are always many improvements possible. The key is to
choose the best ones. Not fixate like a kid in a candy store.

The problem is:
WITH ECC built in, probably over half the cases of "Blue Screen of
Death" or computer crashes and foulups *could* be things of the past!

Even in cases where things like poor capacitors cause spikes, having ECC
memory in the machine would obviate a large portion of those problems.

The original reasons of the extra logic and extra expense just ARE NOT
that relevant any more. They shouldn't even SELL non-ECC memory, for
the relatively tiny price-differential versus the HUGE difference in
reliability. It's like selling retread tires as new ones for almost the
same price. Sure they're CHEAPER ... marginally.

The worst part is, people could actually be KILLED by such mistakes made
by a computer that might have been corrected with ECC ... Yet nobody
will trace it back to that; just: "Sorry, the computer crashed!"

That's unlike a bad tire, which eventually *will* get noticed after
enough people die.

Worse-yet, people aren't even being educated as to what the difference
is. Essentially they're told and even believe that non-ECC memory is
just as good, only cheaper.

"I've ran my computer for years without ECC; and it ran just FINE!"
Only that ignores the freezups, crashes, blue-screens, and other crap
that got attributed to software instead of memory failures. ;-{

These days people seem to *expect* such failures, when 99.99% of the
ones caused by bad memory (probably well over half) could be fixed.

Most people ass-u-me that their memory is good; never EVER running a
memory-test other than the completely useless crap on boot. Hell, most
people, if a computer is crapping out, just replace the whole thing.

In fact, many computer-repair places *encourage* their customers to do
just that ... It makes more money for the company; while running a good
memory-test takes up very valuable technician time and space in the
repair-shop.

For a mere pittance in extra cost these days, especially if ECC memory
was the *standard* instead of the rarely-used, the "extra cost" would be
a huge monetary *gain* instead of a loss. Most especially so in
customer satisfaction.

Still, they don't count "customer satisfaction" as worth a dime these
days, not in comparison to saving ten or twenty cents on a part, do
they?

--
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  #49  
Old October 8th 07, 09:41 PM posted to alt.comp.hardware.homebuilt,alt.comp.hardware,alt.comp.hardware.pc-homebuilt,comp.sys.ibm.pc.hardware.chips
kony
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Posts: 7,416
Default Questions about DDR RAM

On Mon, 08 Oct 2007 18:48:57 GMT, Robert Redelmeier
wrote:

In comp.sys.ibm.pc.hardware.chips Frank McCoy wrote in part:
However, about 99% of memory installed on PCs is *not*
EEC or even parity enabled. They all *should* be.


Oh, pray tell, why? Do you believe you know the PC
business better than Intel, AMD, Dell, HP, ... who have
decided to manufacture chipsets and computers without ECC?


They sell ECC equipped systems too. Would you believe you
knew better if you chose standardized parts instead of
proprietary motherboards, cases and PSU? Most agree on
that. The idea of blindly following an OEM is contrary to
our goals.
  #50  
Old October 9th 07, 01:06 AM posted to alt.comp.hardware.pc-homebuilt
John Doe
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Posts: 4,274
Default Questions about DDR RAM

Frank McCoy wrote:

In alt.comp.hardware.pc-homebuilt Robert Redelmeier
wrote:

In comp.sys.ibm.pc.hardware.chips Frank McCoy
wrote in part:


However, about 99% of memory installed on PCs is *not* EEC or
even parity enabled. They all *should* be.


Do you believe you know the PC business better than Intel, AMD,
Dell, HP, ... who have decided to manufacture chipsets and
computers without ECC?


That's a very good question.

There are always many improvements possible. The key is to choose
the best ones. Not fixate like a kid in a candy store.


Maybe it's one of his brands (like lots of quotation marks and
asterisks).

The problem is: WITH ECC built in, probably over half the cases of
"Blue Screen of Death" or computer crashes and foulups *could* be
things of the past!


With Windows XP, almost all BSODs are a thing of the past. After
years of using Windows XP, I can say "hooray, the stupid operating
system knows how to shut down a program without forcing me to
reboot". I thought the same thing after buying Windows 98 and after
buying Windows ME, but months of use proved that idea to be wishful
thinking.

Even in cases where things like poor capacitors cause spikes,
having ECC memory in the machine would obviate a large portion of
those problems.


I cannot recall seeing data corruption caused by hardware.
Considering the fact that I have frequently copied entire Windows
partitions for about a decade, you might think something that
memory could cause a problem with would go wrong, but it doesn't.
Making sure that the electricity flowing into your computer and out
of your power supply is in good condition can go a long way to
preventing serious malfunction.

For a mere pittance in extra cost these days, especially if ECC
memory was the *standard* instead of the rarely-used, the "extra
cost" would be a huge monetary *gain* instead of a loss. Most
especially so in customer satisfaction.


In that imaginary situation where you are selling PCs, you are
asking people to pay for something they don't need.





 




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