[time-nuts] 5370 processor boards available

cheater00 . cheater00 at gmail.com
Thu Feb 27 10:19:06 EST 2014


You can fit linux with a comfortable amount of stuff in 20 MB, but you want
more than that for more advanced programs.

You should not use the built in ssd for writing. It has limited writes and
cannot be replaced. Use a card.

You can tailor linux so that it has minimal services but the question of
how to make it shut down in a predictable amount of time is a complex issue
and you are best off finding an existing project that focuses on this. So
rather than limit yourself to an esoteric set of requirements I recommend
using a battery that'll run the BBB for 15 minutes and will charge in an
hour while it's on. My day job is among others as a linux admin.

D.
On 27 Feb 2014 15:47, "Didier Juges" <shalimr9 at gmail.com> wrote:

> The BBB has 2GB of flash on board (non removable) and has a micro SD
> socket. Would not be too hard to keep a backup copy of the OS and apps on
> the SD card so that it would be easy to boot from SD and reload the
> built-in flash if the BBB fails to boot from the built-in image.
>
> That would not be a replacement for a workable, safe boot process that can
> be interrupted without trashing the file system. Just a few days ago, an
> overnight storm caused power to flicker maybe 5 times in less than a
> minute. My Raspberry Pi managed to survive it, but I am not sure that will
> always be the case.
>
> I think a super cap with proper shutdown routine would probably the
> easiest to implement. Alternately, running the flash read only, copy OS,
> apps and everything else to a RAM disk and run from the RAM disk would
> probably be the safest. Not sure you can do that with 512MB of RAM without
> some serious pruning of the Linux kernel.
>
> Didier KO4BB
>
>
> On February 27, 2014 2:26:13 AM CST, Hal Murray <hmurray at megapathdsl.net>
> wrote:
> >
> >> I think a better solution would be to find a very large "super cap"
> >and
> >> power the BBB from that while giving it a power fail interrupt to
> >quickly
> >> sync the file system.
> >
> >The advantage of something like the BBB is that it runs Linux so you
> >have a
> >nice environment in which to run your code.  The disadvantage of Linux
> >is
> >that it's complicated and you have things like file systems that can
> >get
> >trashed.  Now, in addition of being the sysadmin for your PC(s), you
> >have to
> >be an admin for your lab gear.  That may be more "interesting" that you
> >were
> >expecting.  A friend reports that his scope caught a virus...
> >
> >The Linux ext4 file system is pretty robust.  There are lots of PCs out
> >there
> >that mostly survive power failures.
> >
> >If I was worried about the file system getting trashed on power off,
> >I'd work
> >on the software long before I added a super-cap.  I think my first try
> >would
> >be to run the file system read-only until I figured out that I needed
> >to
> >write a file.  Then I would know something about how much data I wanted
> >to
> >write and the usage patterns.
> >
> >You can help a lot with flush() in the right places in your code.  That
> >may
> >cost performance if you are writing a lot of data.
> >
> >--------
> >
> >Another approach is to make sure you can put the "disk" back together
> >easily
> >and quickly.  Then it's not such a big deal if/when the disk gets
> >trashed.
> >That's probably a good idea anyway.  Power fail isn't the only thing
> >that can
> >trash a disk.
> >
> >It shouldn't take much more than a simple script to format the disk and
> >copy
> >over all the bits from a backup place on a PC.  Maybe it's install the
> >standard distro package and then add your bits.  (That's assuming you
> >can
> >take the disk out of the BBB and plug it into a PC.)
> >
> >
> >
> >
> >
> >
> >
> >--
> >These are my opinions.  I hate spam.
> >
> >
> >
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