I agree with the cars analogy, in a more specific way...
Ok showing my true colours here but really, we're all nerds of one
stripe or another aren't we? Disclaimer: I'm not the guy in the video,
but am putting together a very similar type of setup on my farm.
If these engines get a good start in life, they can run continuously for
30+years; sometimes oil changes are done by refilling at the same time
as draining out the bottom /while the engine is running/.
I have also operated and maintained forklifts built in the '60s,
operating in scrapyards, abused
and overloaded for their entire working lifetime and still in good
enough condition to
serve the daily needs of the company-50 years running!
The Point:
In our flaky bits and byte world, I must admit that I am amazed at the
durability of some of our last century's 'moving parts' inventions.
The longevity of these machines isn't great for economic
stimulation, but the lifespan is amazing if pride doesn't factor in, and
you have no need to live with the latest.
Nowhere in this does a bathtub factor in, but the old iron: there is
longevity I can appreciate, feel, and hear.
p.s.: mechanic's insider knowledge!: subaru boxer engines WILL give
at least 500,000 km of reliable service, with regular oil change(just do
the filter every 2-3 oil changes and add sheet metal to rust holes
that may pop up in the doors).
J.J.
Send Roundtable mailing list submissions to
roundtable@muug.mb.ca
To subscribe or unsubscribe via the World Wide Web, visit
http://www.muug.mb.ca/mailman/listinfo/roundtable
or, via email, send a message with subject or body 'help' to
roundtable-request@muug.mb.ca
You can reach the person managing the list at
roundtable-owner@muug.mb.ca
When replying, please edit your Subject line so it is more specific
than "Re: Contents of Roundtable digest..."
Today's Topics:
- hard drive failure curve (Trevor Cordes)
- Re: hard drive failure curve (Adam Thompson)
- Re: hard drive failure curve (Trevor Cordes)
- Re: hard drive failure curve (Adam Thompson)
---------- Forwarded message ----------
From: Trevor Cordes trevor@tecnopolis.ca
To: MUUG RndTbl roundtable@muug.mb.ca
Cc:
Date: Wed, 3 Sep 2014 14:10:53 -0500
Subject: [RndTbl] hard drive failure curve
OK, so you know how many (most?) computer components' failure rates
follow the "bathtub curve":
http://users.ece.cmu.edu/~koopman/des_s99/sw_reliability/Image1.gif
They either die quickly due to egregious manufacturing faults, or live
a long time (near 0% failure rate), and then all start dying as they get
really old.
The bathtub curve occurs in tons of places, like with a simple light
bulb.
As per my experience (probably dealing with over 1000 drives
personally), and google's studies, as well as anecdotal information,
hard drives are different. The failure rate seems to be bathtub-ish.
The initial failure rate is fairly bathtub. But the useful-life period
is at a much higher level and seems to grow slightly, meaning instead
of dropping to near-zero failures during useful life, they drop to
around 15% failure rate each year, mostly independent of age. Then,
in the old-age phase they seem to ramp up much slower towards death.
It's not a hockey-stick right edge, it's more a constant gentle hill
slope. We all have seen many drives that are still running after 8,
10, 20 years. In fact, it seems more of a survival of the fittest
system (maybe like turtles?), where once they live to a certain age,
many go on to live far beyond the average.
Anyhow, my question is, what else in the non-computer world has a
failure graph like hard drives? Something easy for a neophyte to grasp.
Normal bathtubs have lightbulbs. What analogy can be used for hard
drives? I haven't been able to think of any!
Surely there must be one??
---------- Forwarded message ----------
From: Adam Thompson athompso@athompso.net
To: Continuation of Round Table discussion roundtable@muug.mb.ca, Trevor Cordes trevor@tecnopolis.ca
Cc:
Date: Wed, 03 Sep 2014 14:53:21 -0500
Subject: Re: [RndTbl] hard drive failure curve
The obvious analogy that for obvious reasons* won't have occurred to you: cars. If you don't get a lemon, it's probably good for a while, but eventually starts to break down.
Also, historically, humans - at least in ages and places where infant mortality is/was a significant drag on population growth.
-Adam
*for those of you who don't know Trevor well, his 25(?)-year-old car is lovingly & painstakingly maintained in near-new condition.
On September 3, 2014 2:10:53 PM CDT, Trevor Cordes trevor@tecnopolis.ca wrote:
OK, so you know how many (most?) computer components' failure rates
follow the "bathtub curve":
http://users.ece.cmu.edu/~koopman/des_s99/sw_reliability/Image1.gif
They either die quickly due to egregious manufacturing faults, or live
a long time (near 0% failure rate), and then all start dying as they get
really old.
The bathtub curve occurs in tons of places, like with a simple light
bulb.
As per my experience (probably dealing with over 1000 drives
personally), and google's studies, as well as anecdotal information,
hard drives are different. The failure rate seems to be bathtub-ish.
The initial failure rate is fairly bathtub. But the useful-life period
is at a much higher level and seems to grow slightly, meaning instead
of dropping to near-zero failures during useful life, they dr!
op to
around 15% failure rate each year, mostly independent of age. Then,
in the old-age phase they seem to ramp up much slower towards death.
It's not a hockey-stick right edge, it's more a constant gentle hill
slope. We all have seen many drives that are still running after 8,
10, 20 years. In fact, it seems more of a survival of the fittest
system (maybe like turtles?), where once they live to a certain age,
many go on to live far beyond the average.
Anyhow, my question is, what else in the non-computer world has a
failure graph like hard drives? Something easy for a neophyte to grasp.
Normal bathtubs have lightbulbs. What analogy can be used for hard
drives? I haven't been able to think of any!
Surely there must be one??
________________________________
Roundtable mailing list
Roundtable@muug.mb.ca
http://www.muug.mb.ca/mailman/listinfo/roundtable
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
---------- Forwarded message ----------
From: Trevor Cordes trevor@tecnopolis.ca
To: MUUG RndTbl roundtable@muug.mb.ca
Cc:
Date: Thu, 4 Sep 2014 02:23:21 -0500
Subject: Re: [RndTbl] hard drive failure curve
On 2014-09-03 Adam Thompson wrote:
The obvious analogy that for obvious reasons* won't have occurred to
you: cars. If you don't get a lemon, it's probably good for a while,
but eventually starts to break down. Also, historically, humans - at
least in ages and places where infant mortality is/was a significant
drag on population growth.
The Cars example is imperfect, because, as you said "it's good for a
while", but with hard drives I find that the near-zero-failure part of
the bathtub, if it even exists for HDDs, is abominably short, like 6
months. Most quality cars these days (ones ranked high in Consumer
Reports reliability) should be nearly trouble-free for 5 years.
Here's my interpretation of the HD curve (monospace required):
|
| ____________________________
\ __________/
\ _________/
\ /
__/
The main point being that after (maybe) a short reprieve, the failure
probability immediately ramps up to and sits at an unacceptable number
(like 15%) nearly forever, with but a tiny increment after each
additional year. Whether there is a bathtub end after 10-20 years, is
up for debate. (Brad and I have Atari ST drives from 30 years ago that
still operate, for example.)
Surely if you ASCII'd a modern car graph it wouldn't quite fit?
Your human being analogy is probably much closer to what I'm looking
for, but that one definitely has an abrupt bathtub hockey-stick at the
right hand side :-) With humans, make it past the first tricky year
and you probably have a small chance that stays relatively static for
dozens of years of contracting a terminal illness or getting hit by a
bus. Not as straight-forward as a "light bulb" example as I was
looking for (as it requires some thought and reflection) but pretty
good.
Surely, though, in the world of consumer items something else must be
just like hard drives?
---------- Forwarded message ----------
From: Adam Thompson athompso@athompso.net
To: roundtable@muug.mb.ca
Cc:
Date: Thu, 04 Sep 2014 02:41:02 -0500
Subject: Re: [RndTbl] hard drive failure curve
On 14-09-04 02:23 AM, Trevor Cordes wrote:
The Cars example is imperfect, because, as you said "it's good for a
while",
Yup. Closest mass good I could think of offhand.
Surely if you ASCII'd a modern car graph it wouldn't quite fit?
The key difference is that you can repair and maintain a car, whereas a HDD (or SSD, for that matter) is either alive and well, alive and dying, or dead - and there's nothing you can do about it.
Your human being analogy is probably much closer to what I'm looking
for, but that one definitely has an abrupt bathtub hockey-stick at the
right hand side :-)
Yessss... although not so abrupt, at various points in history.
Surely, though, in the world of consumer items something else must be
just like hard drives?
Not that I can think of. You have to combine a) non-negligible failure rate, with b) extremely tight tolerances, with c) variable quality control on (b), to get a similar result. Outside the computing field, I can't think of anything [other than cars] that has as much complexity, as "finicky" as 10,000rpm spinning platters - AND is common enough that everyone will understand it.
--
-Adam Thompson
athompso@athompso.net
Roundtable mailing list
Roundtable@muug.mb.ca
http://www.muug.mb.ca/mailman/listinfo/roundtable
Jean Jubinville