Most energy efficient (home) setup

Thu Apr 19 03:09:44 UTC 2012

On Apr 18, 2012, at 5:55 32PM, Douglas Otis wrote:

> On 4/18/12 12:35 PM, Jeroen van Aart wrote:
>> Laurent GUERBY wrote:
>> > Do you have reference to recent papers with experimental data about
>> > non ECC memory errors? It should be fairly easy to do
>> Maybe this provides some information:
>> 
>> http://en.wikipedia.org/wiki/ECC_memory#Problem_background
>> 
>> "Work published between 2007 and 2009 showed widely varying error
>> rates with over 7 orders of magnitude difference, ranging from
>> 10−10−10−17 error/bit·h, roughly one bit error, per hour, per
>> gigabyte of memory to one bit error, per century, per gigabyte of
>> memory.[2][4][5] A very large-scale study based on Google's very
>> large number of servers was presented at the
>> SIGMETRICS/Performance’09 conference.[4] The actual error rate found
>> was several orders of magnitude higher than previous small-scale or
>> laboratory studies, with 25,000 to 70,000 errors per billion device
>> hours per megabit (about 3–10×10−9 error/bit·h), and more than 8% of
>> DIMM memory modules affected by errors per year."
> Dear Jeroen,
> 
> In the work that led up to RFC3309, many of the errors found on the Internet pertained to single interface bits, and not single data bits.  Working at a large chip manufacturer that removed internal memory error detection to foolishly save space, cost them dearly in then needing to do far more exhaustive four corner testing.  Checksums used by TCP and UDP are able to detect single bit data errors, but may miss as much as 2% of single interface bit errors.  It would be surprising to find memory designs lacking internal error detection logic.

mallet:~ smb$ head -14 doc/ietf/rfc/rfc3309.txt | sed 1,7d | sed 2,5d; date
Request for Comments: 3309                                      Stanford
                                                          September 2002

Wed Apr 18 23:07:53 EDT 2012

We are not in a static field...  (3309 is one of my favorite RFCs -- but
the specific findings (errors happen more often than you think), as
opposed the general lesson (understand your threat model) may be OBE.

		--Steve Bellovin, https://www.cs.columbia.edu/~smb