Disk flush intervals
You can change disk flush intervals through the proc filesystem. The following will shorten its interval from the default five seconds to one second.
# echo "40 0 0 0 100 30000 60 0 0" > /proc/sys/vm/bdflush
This may negatively impact file I/O performance a little bit. But this secures file contents except for the last one second which is shorter than the default five seconds. This is true even for journaling filesystems.
