[nvmewin] NVMe Windows driver copy progress issue

[Mike Berhan]

Regarding changes in the miniport, you could make the device look like it
has removable media to the OS (Removable bit in STOR_DEVICE_CAPABILITIES and
Inquiry page).  If you do, then the "Policies" page for the disk device in
device manager will allow you to enable "Quick removal" which states:

"Disables write caching on the device and in Windows..."

This will have other implications which may not be desirable, such as the
device appearing in the taskbar eject media options.  Experiment with it if
you like.  There may be other options that would do the same thing.

What are you trying to accomplish?  If it's benchmarking, why not use a
benchmark app that accesses the physical disk directly?

Mike

-----Original Message-----
From: mithun.davis at keysight.com [mailto:mithun.davis at keysight.com] 
Sent: Monday, October 20, 2014 12:42 PM
To: mikeb at bustrace.com; nvmewin at lists.openfabrics.org
Subject: RE: [nvmewin] NVMe Windows driver copy progress issue

Hi Mike,

I did try this out. When copying with /j the command returns only after copy
is actually over while when this switch is not used, xcopy returns
immediately. So I think you are right, the cause of the issue is buffering.

Is there some way we can prevent buffering for specific drives or can we
switch this off in the driver?

Thanks for your help.

Regards,
Mithun

-----Original Message-----
From: nvmewin-bounces at lists.openfabrics.org
[mailto:nvmewin-bounces at lists.openfabrics.org] On Behalf Of Mike Berhan
Sent: Saturday, 18 October, 2014 8:39 PM
To: nvmewin at lists.openfabrics.org
Subject: Re: [nvmewin] NVMe Windows driver copy progress issue

That's because you are dealing with buffered writes.  Try using xcopy /j to
perform your copy.

http://technet.microsoft.com/en-us/library/cc771254(WS.10).aspx

I wrote a simple batch file to copy a 512MB file from a RAM drive to an NVMe
drive and do it 6 times.  These are the timings:

1080 msec (with /j)
280 msec
310 msec
280 msec
2160 msec (with /j)
280 msec

The 5th timing is double the 1st timing because it is now competing for
bandwidth from the buffered writes that preceded it.

Mike

From: nvmewin-bounces at lists.openfabrics.org
[mailto:nvmewin-bounces at lists.openfabrics.org] On Behalf Of
mithun.davis at keysight.com
Sent: Friday, October 17, 2014 4:13 AM
To: nvmewin at lists.openfabrics.org
Subject: [nvmewin] NVMe Windows driver copy progress issue

Hi,

I am faced with a particular problem with the NVMe driver for Windows. I am
using the 1.3 revision of the driver. When I copy a large file onto the
device, it appears to have been copied in windows explorer but in the
background the driver still seems to be copying it. The device being used is
not very fast to respond which is the cause of the slow speed. Can anyone
please help with why the file appears to be copied in windows explorer? I
would like it to show the copy status as close to actual as possible.

Thanks in advance for your help.

Regards,
Mithun

_______________________________________________
nvmewin mailing list
nvmewin at lists.openfabrics.org
http://lists.openfabrics.org/mailman/listinfo/nvmewin