samba - May 2010 - Magic parameter "-ec" of IOZone to increase the write performance of samba

Hi,

I am measuring the performance of my newly bought NAS with IOZone.
The NAS is of an embedded linux with samba installed. (CPU is Intel Atom)
The IOZone reported that write performance to be over 1GBps while the file
size less or equals to 1GB.
Since the nic is 1Gbps, the maximum speed is supposed to be 125MiBps at
most.
The testing report of IOZone is amazing.

Later I found that If the testing parameters of IOZone contains the
"-c" or
"-e" or "-ec",
the write performance reduced to a reasonable speed, it's around 55MBps.
The "-c" means "includes the close time", "-e"
means "inlcudes the fflush
time".

That's cool. It seems that some kind of tuning in somewhere of the samba
file server (NAS)
can drive the IOZone to be crazy and report such amazing numbers.

Does anyone know how they make it?

I mount the samba share folder in NAS with "mount -t cifs -o
rsize=65536,username=xxx" to do the test.
I did the testing in a CentOS 5.3 desktop. I also tested in Vista and it
yielded same incredible result of the write performance.