Q:

What file system format should I use on flash memory?

This is for a data logger application running under latest Debian/Raspbian.  The app will run long term and write about 1M of ASCII per day to a large flash drive (say, 32GB).  There will be few reads, just when the data is downloaded every few weeks.  The priority is the integrity of the logged data.

A:

Linux:
EXT2 (2 TB limit & non-journaling)
I would go with this since you most probably want a lower power system for logging.
or
EXT3/EXT4 (disable journal for more writes)
EXT4 has more performance than EXT3 but EXT3 uses less power.
tune2fs -O ^has_journal /dev/sdbX

/etc/fstab
/dev/sdbX          /dir/         ext3      defaults,noatime    0      0
/dev/sdbX          /dir/         ext4      defaults,noatime    0      0

Any OS:
FAT16/FAT32

A:

You should take into account on which OS you want to read the data. Then, you have to decide whether you want to support journaling or not. Take into account that with journaling:

lower performance at write time, since there is the extra work of the journal
increased chance of damaging the flash memory due to extra use of the journal causing wearing
increased space usage (for the journal)

It is my understanding that you want to employ journaling, since integrity is your priority. Hence, if you are going to read the data under Linux, ext4 seems jut fine to me.

