[time-nuts] Beaglebone NTP server
hmurray at megapathdsl.net
Thu Dec 11 16:23:25 EST 2014
jimlux at earthlink.net said:
> Ah, but will the exact same single board computer be available for
> replacement in 5 years? Or will it be Rev F instead of Rev B, with "just a
> few tweaks to improve performance", but also enough that it's not "drop the
> image on it and run"
> What about 10 years? 15?
My straw man is to buy a bunch now and put them on the shelf until you need
them? It would be interesting to read a good B-school type report on that
Is it realistic to expect any electronics related stuff to be available for
10 years? I think I've seen a few boards marked long-lifetime. I don't
remember the details. At least one OS distro has a version marked
long-lifetime, but I don't know how long that covers.
What does the military do for this problem? What's the average lifetime of
something like a radio in a military plane? How often do they get upgraded
because the old ones are no longer maintainable due to unavailability of
What's the average lifetime of a fab line? Or even the max lifetime? (in
case you are a big vendor with multiple fab lines for a particular technology)
What's the typical lifetime of parts used in timing related gear?
> Maybe that's the key.. think of it as an appliance. If it stops working,
> and it's not because of something simple (power cord), then you're probably
> better off building a new one from scratch than trying to fix the old one.
> That is, the labor involved in "port to a new platform" might be
> substantially less than "find old platform and install it in old box", if
> only because things like tool chains tend to follow the latest hardware.
A lot of that depends on the quality of the documentation you kept when you
set things up.
I've worked with guys who were good at making a big pile of kludgy gear jump
through hoops. One of them was very good at writing down what he did. It
doesn't have to be a fancy document blessed by 43 proofreaders, but it really
helps to mention all the critical steps and/or explain the non-obvious
reasons for doing things.
I've gotten into the habit of making a checklist of what I have to do to
install distro-X from CD and fix it up to do what I want. Every now and
then, I want another box just like that one except...
It isn't fancy, but it does have a line to remind me about each file that
needs editing and what tools are used to set things up. Often there are
chunks of code I can cut-paste.
> Even if you kept the tool chain for your old platform, running it on a new
> computer might be problematic. (recognizing that there are people out there
> running IBM 1401 emulators on System/360 emulators on... but that takes
> time too)
It's not uncommon to archive the PC that has all the tools when a significant
hardware project is released. Just put a big note on it and push it into a
closet in case you ever need it again. (Setting up CAD tools is often quirky
and hard to debug.) Again, this needs documentation. Suppose you want to
make a simple one line change to fix a typo. What do you do to turn the
crank and make the files you hand off to the next step?
These are my opinions. I hate spam.
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