[152208] in North American Network Operators' Group
Re: Most energy efficient (home) setup
daemon@ATHENA.MIT.EDU (Steven Bellovin)
Wed Apr 18 23:11:43 2012
From: Steven Bellovin <smb@cs.columbia.edu>
In-Reply-To: <4F8F3854.3030208@mail-abuse.org>
Date: Wed, 18 Apr 2012 23:09:44 -0400
To: Douglas Otis <dotis@mail-abuse.org>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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:
>>=20
>> http://en.wikipedia.org/wiki/ECC_memory#Problem_background
>>=20
>> "Work published between 2007 and 2009 showed widely varying error
>> rates with over 7 orders of magnitude difference, ranging from
>> 10=E2=88=9210=E2=88=9210=E2=88=9217 error/bit=C2=B7h, 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=E2=80=9909 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=E2=80=9310=C3=9710=E2=88=929 =
error/bit=C2=B7h), and more than 8% of
>> DIMM memory modules affected by errors per year."
> Dear Jeroen,
>=20
> 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
