In message , Adrian
 writes
>With it all connected up (and the router tweaked to reflect the new MAC
>address), I've rerun the rsync, and it works.  However, as this is
>intermittent, that proves nothing in the short term.
>

It has now run for a week, and I've yet to see a rsync operation fail,
so (as predicted by some), it appears to be a hardware problem.

There have however been some other oddities (none of which appear to be
problems), which may be of interest to some.

I gather a series of stats from each Pi every minute, so over time,
performance patterns can be seen.  These stats include CPU and GPU
temperature, ping time (ping -c 1 $ROUTER) and the number of bytes in
and out.

The target Pi, which has had it's OS upgrade to Buster has gone from a
typical minimum ping time for the day of ~.450mS to ~.650mS.  Other Pis
have remained at their usual sort of times.

The source Pi (new SD card and new Pi) has changed from having the CPU
and GPU temperature within 0.1 degrees of each other to now being ~5
degrees apart (CPU always lower than GPU).  All other Pis are usually
consistent in the 0.1 degree variation.

Other PIs on my network which have a basically static workload (e.g. the
weather station), are showing interesting results around their daily
rsync operations.  Comparing (e.g.) Monday against Monday, I'm seeing
the number of bytes being transferred dropping significantly during the
operation, Incoming bytes by 17% and outgoing by 8%.  Looking at the
logs, the number of files being rsync'd is consistent, so unless those
files have shrunk significantly (and I see no reason as to why they
might have), then it looks as though the operation of the rsync process
has improved significantly.  The percentages vary from Pi to Pi, but in
all cases, there is a noticeable downward trend in the network traffic
at rsync time.

Adrian
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