Hello David,

DR>>> When copying between cards, it is common to find that no two of the same
DR>>> stated capacity have exactly the same number of sectors, and you can't
DR>>> perform an exact copy from a larger card to a smaller one.

HD>> I know for many years.
HD>> That often happened when using different makes and/or types,
HD>> but I seldom do that.

DR>>> To get around this, after setting up an Pi image and allowing it to
DR>>> expand to the size of the card, I then remove it and use gparted to
DR>>> shrink the last partition by 1M. This means it can safely be copied to a
DR>>> slightly smaller card without losing anything vital.

HD>> I know this tric and I sometimes did.
HD>> But nowadays I allways use the same make, type and capacity of
HD>> microSDcards.

In my archives I found this:

7.969.177.600 Bytes at Kingston 8 GB C10
1st Fat partition is 56 MB
2nd EXT partition is rest
According  RISC OS !CloneDisc
7.421 GiB
15.564.800 sectors

Kingston 8 GB C4
Accordimg  RISC OS !CloneDisc
7.318 GiB
15.347.712 sectors

Intenso 8 GB C4
7.746.879.488 Bytes write
According  RISC OS !CloneDisc
7.214 GiB
15.130.624 sectors

So the differences are very much more then your mentioned 1 MB ;-(.
That's why I always buy the same make, type and capacity Kingston microSDcards
from the same supplier, a shop 10 km from here, and mostly four at a time. I
often need them to create an AIS+ECDIS system with Rasbian Linux + OpenCPN
ECDIS-viewer and most European governmental S57 inland waterway charts and
also the OpenSeaMap charts from .NL and .BE for the smaller canals, rivers
and lakes to support the skippers of old recreational ships, former cargo
ships and old tugs etc. See .
The Netherlands has the largest collection of historical ships in the world.
At that website there is also a chapter about AIS+ECDIS.
I am one of the members of that club, and made OpenCPN ECDIS viewer work under
Raspbian Wheezy on the Pi 1B in december 2014 for our skippers.
I am now with version 5 of the 16 GB SDcard using Raspbian Stretch, and just
compiled OpenCPN 4.99.0 to it, together wich many inland ECDIS charts of
Western Europe. That S57 + OSM charts alone take 3.4 GB !
It consists of maps from The Netherlands, Belgium, France, Germany,
Switserland, Austria and Poland. But there are more if you wisch to install,
i.e. south east Europ countries.
I did not research if there are inland water charts for England, Norway and
Sweden?
So there is very much to sail to and on.
Good luck in copying (micro-)SDcards.

Henri.

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