[aprssig] Quick APRS hardware survey (APRS Hotspot)

Jason KG4WSV kg4wsv at gmail.com
Thu Jun 22 14:59:01 CDT 2017

On Thu, Jun 22, 2017 at 2:36 PM, Greg Trasuk <trasukg at trasuk.com> wrote:
> Could you expand on this?  I did the calculations, and a reasonable SD card should have enough write cycles for several years.  Why would the system need to be read-only?

It's not write-cycle, although the pi can kill an SD card in a short
period of time (e.g. don't run disk IO benchmarks unless you actually
intend to kill the card).  I don't know if SD has wear leveling, or if
it's up to the capabilities of SSD wear leveling if it does.

The problem is the intolerance to power outages due to the buffering.
Apparently the buffering is taking place inside the SD card where the
OS can't influence it (e.g. sync doesn't work).  If power gets dropped
you can (eventually _will_ is my understanding) corrupt the filesystem
so that it requires a "disk" rebuild to recover.  Think your unix
system 30 years ago, at least that's the impression I get.  I thought
about setting up a test, but haven't gotten around to it.

> Arguably, for “enterprise" use, you’d want a hard-wired ethernet cable anyway.

yeah, but there's this whole IoT thing going on and lesser priority
sensors are a good fit for wifi, even in the enterprise (IMO).  I
wouldn't use it on an infrastructure server UPS, but for an access
control system box that's located in a mechanical closet with no CAT5,
I can throw a pi at it and be able to get health and status info from
the battery so I have a chance to replace it before I start getting
reports of "I can't get in the lab HELP!!!!" without dropping $450 to
get a CAT5 drop and an APC NIC.

> FWIW, at Burlington Amateur Radio Club, we’ve had a couple of Pis at our remote location (one for APRS, one for D-Star) for about a year now, with few actual Pi-related problems.  We did have to replace a cheap SD card with a name-brand card, and we’re currently having trouble with a cheap Chinese USB-Serial interface.  In general, though, the Pi’s have been pretty solid.

That's good info. I have wondered about their tolerance of heat, but I
have no information so I didn't comment.

I do have a beaglebone black that I've got racked up in my server room
(solves the "quis custodiet ipsos custodes" problem in my nagios
configuration) that had performed extremely reliably for the past few
years.  It's more expensive (therefore less popular), has no wifi, and
is less powerful than a Pi 3, but it's got a reliable flash memory
system that's soldered on, plus it has a couple of bare metal cores
intended for DSP operations if you're into that sort of thing.  A ham
(can't remember who or where) is using it for high speed digital mode


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