ASPI and STPI transfer size

NTDEV
1

Hi!

I’ve wrote own ASPI layer for Windows NT/2K. Works fine except one detail.
According to ASPI spec it’s always safe to use 64KB transfer but SPTI
cannot handle more then SCSI miniport does, so sometimes SPTI’s maximum
transfer cannot be 64KB. Is there any way to increase the number of bytes
SPTI can move?

Regards,
Anton

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2

Only be increasing the miniport’s maximum transfer. Sometimes there are registry
entries that can be set for the miniport (eg “MaximumSGList”) – 255 is the max
value (255 * 4KB == 1MB - 4KB).

Regards,

Paul Bunn, UltraBac.com, 425-644-6000
Microsoft MVP - WindowsNT/2000
http://www.ultrabac.com

-----Original Message-----
From: xxxxx@hotmail.com
[mailto:xxxxx@hotmail.com]
Sent: Monday, January 22, 2001 9:49 PM
To: NT Developers Interest List
Subject: [ntdev] ASPI and STPI transfer size

Hi!

I’ve wrote own ASPI layer for Windows NT/2K. Works fine except one detail.
According to ASPI spec it’s always safe to use 64KB transfer but SPTI
cannot handle more then SCSI miniport does, so sometimes SPTI’s maximum
transfer cannot be 64KB. Is there any way to increase the number of bytes
SPTI can move?

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3

I know this way. Sometimes it helps, sometimes it does not help.
It does not help for example for virtual SCSI miniports used for
SCSIizing other hardware (like USB & LPT CDRWs). I’m even proud
author of one of this miniports that cannot handle 64KB xfers.

So any other ideas except breaking the transfer to more then one
at ASPI level?

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