emonSD-17Oct19 Image partition sizes

Emoncms Installation
6

I have had a chance to try this out and the sizes above are not correct. This added to the init_resize.sh script will work.

#EmonSD Fix end of Rootfs
if [ $ROOT_DEV_SIZE -gt 16000000 ]; then
  #16GB card or above, assign last 10GB for data 
  TARGET_END=$(($ROOT_DEV_SIZE - 20972544 - 1 ))
elif [ $ROOT_DEV_SIZE -gt 8000000 ]; then
  #8GB card, assign last 4GB for data 
  TARGET_END=$(($ROOT_DEV_SIZE - 7341056 - 1 ))
fi

The original sizes I proposed did not align optimally.

For future ref, the key figure is 2048. parted wants the start of a partition to start on a multiple of 2048. Because of the calculation, and the fact the whole SD card is not a multiple of 2048, this caused a problem as the rootfs did not finish on a 2048 boundary.

The Ext2 partition is not a multiple of 2048 (it doesn’t need to be).

I am, however, not convinced this is robust for all SD cards - it assumes that the whole card is not a multiple of 2048 - I hate assumptions!

Can anyone suggest a way in bash to check the alignment figure?

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