ext3 only allows dirty data to remain in memory for five seconds,
whereas the other filesystems allow it for thirty. This is
a reasonable thing to do, but it hurts badly in benchmarks.
If you run a benchmark which takes ext2 ten seconds to
complete, ext2 will do it all in-RAM. But after five
seconds, ext3 will go to disk and the test takes vastly longer.
I suspect that is what is happening here - we're seeing the
difference between disk bandwidth and memory bandwidth.
If you choose a larger file, a shorter file or a longer-running
test then the difference will not be so gross.
You can confirm this by trying a one-gigabyte file instead.
The "Initial write" is fishy. I wonder if the same thing
is happening here - there may have been lots of dirty memory
left in-core (and unaccounted for) after the test completed.
iozone has a `-e' option which causes it to include the fsync()
time in the timing calculations. Using that would give a
better comparison, unless you are specifically trying to test
in-memory performance. And we're not doing that here.
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