Very slow write disc access with buffering

[Guest]

Hi there,

I experiment VERY slow write disc access.

To narrow down the problem I wrote a small program to write a file by block
of
16MB.

The test program uses the Win32 API CreateFile/WriteFile/CloseHandle.
CreateFile can have a flag buffering/no buffering FILE_FLAG_NO_BUFFERING
(FILE_FLAG_WRITE_THROUGH doesn't change anything to my tests).
When writting :
- with buffering it's SLOW and about the same speed on any drive.
- without buffering it's FULL speed with different speed depending on drive.
- results seems to be OK when writing through a mapped network drive from
another computer whatever the buffering flag is.

Results:
windows buffering is changed with the flag FILE_FLAG_NO_BUFFERING
disc cache writting is changed in : Device Manager->Disc Drives->Any
drive->Properties->Policies->Enable write caching on the disc.
the disc drive for the speed is stripped 400GB HD, speed is ~140MB/s

with buffering with caching ~ 2.4s/16MB PROBLEM HERE
without buffering with caching ~ 0.13s/16MB OK
with buffering without caching ~ 2.4s/16MB PROBLEM HERE
without buffering without caching ~ 1.2s/16MB (very slow but why not!)

So the problem is UNDER the Win32 API but ABOVE the driver or the disc drive !

I'm have absolutely no idea of what the problem could be!
Any idea someone ?

Thank very much

Patrick

Config:
Machine : Dell Precision 690
OS : Win XP SP2
All updates installed, all drivers up to date
CPU : Xeon 3.7GHz, 2GB of RAM
4 HDs, 2 x 230GB + 2 x 372 GB stripped

 

[TERRI HOJABOOM]

I'm have absolutely no idea of what the problem could be!
Any idea someone ?

http://support.microsoft.com/?kbid=817472

http://forum.imgburn.com/index.php?showtopic=4032