Perhaps a more "sysadmin-ish" answer would have been something more like "Whatever the command 'echo 1 > /tmp/one && du -h /tmp/one && rm /tmp/one' prints".
echo "a" > a; du -sh a; rm a
2.0K a
dumpe2fs /dev/sda1 | grep -i 'Block size'
Block size: 1024
$ du -sh /tmp/a
4.0K a
$ tune2fs -l /dev/mapper/VolGroup00-LogVol00 | grep "Block size"
Block size: 4096
I get similar behavior on the other partition:
echo "a" > a; du -sh a
8.0K a
dumpe2fs /dev/VolGroup00/LogVol00 | grep "Block size"
Block size: 4096
Though if I 'touch' the files to create them, they are the blocksize. Which seems odd, since on my AIX and HP-UX boxes that gives files of size 0.