Multipath IO: IRP_MJ_READ and IRP_MJ_WRITE

Hi All,

I am working on a DSM driver and have a basic query on it.

Will the IRP_MJ_READ and IRP_MJ_WRITE pass through the mpio drivers or not?
When I tested with the sample DSM and found that the IRP_MJ_READ and
IRP_MJ_WRITE are not passed through any of the MPIO driver files
(mpspfltr.sys, mpdev.sys and mpio.sys) but it is handled by the disk.sys and
ntfs.sys.

When I checked with the “Device Tree” the mpdev.sys is not installed at
all. It would be of great help, if anyone can tell the expected behavior in
a final setup. I feel there is some problem in this behavior, since the
mpdev.sys should replace the disk.sys functionality. Is my assumption
correct or not?

Any comments would be of great help.

Thanks in advance

Ramesh


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Below disk.sys IO uses IRP_MJ_SCSI. Read the disk.sys source code, it is in
the ddk.

=====================
Mark Roddy
Windows .NET/XP/2000 Consulting
Hollis Technology Solutions 603-321-1032
www.hollistech.com

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Ramesh K
Sent: Thursday, January 27, 2005 2:46 AM
To: Windows System Software Devs Interest List
Subject: [ntdev] Multipath IO: IRP_MJ_READ and IRP_MJ_WRITE

Hi All,

I am working on a DSM driver and have a basic query on it.

Will the IRP_MJ_READ and IRP_MJ_WRITE pass through the mpio
drivers or not?
When I tested with the sample DSM and found that the
IRP_MJ_READ and IRP_MJ_WRITE are not passed through any of
the MPIO driver files (mpspfltr.sys, mpdev.sys and mpio.sys)
but it is handled by the disk.sys and ntfs.sys.

When I checked with the “Device Tree” the mpdev.sys is not
installed at all. It would be of great help, if anyone can
tell the expected behavior in a final setup. I feel there is
some problem in this behavior, since the mpdev.sys should
replace the disk.sys functionality. Is my assumption correct or not?

Any comments would be of great help.

Thanks in advance

Ramesh


Find what you are looking for with the Lycos Yellow Pages
http://r.lycos.com/r/yp_emailfooter/http://yellowpages.lycos.c
om/default.asp?SRC=lycos10


Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

You are currently subscribed to ntdev as: unknown lmsubst tag
argument: ‘’
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Hi Mark,

Thanks for your reply.

> Below disk.sys IO uses IRP_MJ_SCSI.

That’s correct but as per Microsoft documentation (How to Write a
Microsoft MPIO DSM - Part 1.ppt) mpdev.sys is a replacement class
driver and it keeps disk.sys from loading. Doesn’t it imply
that mpdev.sys does the job of disk.sys in the case of mpio.
That’s why I am expecting mpdev.sys to handle the job
IRP_MJ_READ and IRP_MJ_WRITE.

Thanks
Ramesh
----- Original Message -----
From: “Mark Roddy”
To: “Windows System Software Devs Interest List”
Subject: RE: [ntdev] Multipath IO: IRP_MJ_READ and IRP_MJ_WRITE
Date: Thu, 27 Jan 2005 07:22:07 -0500

>
> Below disk.sys IO uses IRP_MJ_SCSI. Read the disk.sys source code, it is in
> the ddk.
>
> =====================
> Mark Roddy
> Windows .NET/XP/2000 Consulting
> Hollis Technology Solutions 603-321-1032
> www.hollistech.com
>
> > -----Original Message-----
> > From: xxxxx@lists.osr.com
> > [mailto:xxxxx@lists.osr.com] On Behalf Of Ramesh K
> > Sent: Thursday, January 27, 2005 2:46 AM
> > To: Windows System Software Devs Interest List
> > Subject: [ntdev] Multipath IO: IRP_MJ_READ and IRP_MJ_WRITE
> >
> > Hi All,
> >
> > I am working on a DSM driver and have a basic query on it.
> >
> > Will the IRP_MJ_READ and IRP_MJ_WRITE pass through the mpio drivers or not?
> > When I tested with the sample DSM and found that the IRP_MJ_READ
> > and IRP_MJ_WRITE are not passed through any of the MPIO driver
> > files (mpspfltr.sys, mpdev.sys and mpio.sys) but it is handled by
> > the disk.sys and ntfs.sys.
> >
> > When I checked with the “Device Tree” the mpdev.sys is not
> > installed at all. It would be of great help, if anyone can tell
> > the expected behavior in a final setup. I feel there is some
> > problem in this behavior, since the mpdev.sys should replace the
> > disk.sys functionality. Is my assumption correct or not?
> >
> > Any comments would be of great help.
> >
> > Thanks in advance
> >
> > Ramesh
> >
> >
> > –
> >
> > Find what you are looking for with the Lycos Yellow Pages
> > http://r.lycos.com/r/yp_emailfooter/http://yellowpages.lycos.c
> > om/default.asp?SRC=lycos10
> >
> >
> > —
> > Questions? First check the Kernel Driver FAQ at
> > http://www.osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as: unknown lmsubst tag argument: ‘’
> > To unsubscribe send a blank email to xxxxx@lists.osr.com
> >
>
>
>
>
> —
> Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@lycos.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com



Find what you are looking for with the Lycos Yellow Pages
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Unless I am mistaken mpio remains under an NDA, so we really cannot discuss
the details here, right?

On the otherhand replacement means replacing existing functionality. I
really can’t see how a replacement for disk.sys could not continue to
perform the existing disk.sys functionality of translating read/write IRPS
from the volume device into srb irps for the port driver. But as you have
access to the mpio docs and samples, this should all just be a matter of
reading comprehension.

=====================
Mark Roddy
Windows .NET/XP/2000 Consulting
Hollis Technology Solutions 603-321-1032
www.hollistech.com

-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Ramesh K
Sent: Friday, January 28, 2005 3:43 AM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] Multipath IO: IRP_MJ_READ and IRP_MJ_WRITE

Hi Mark,

Thanks for your reply.

>> Below disk.sys IO uses IRP_MJ_SCSI.

That’s correct but as per Microsoft documentation (How to
Write a Microsoft MPIO DSM - Part 1.ppt) mpdev.sys is a
replacement class driver and it keeps disk.sys from loading.
Doesn’t it imply that mpdev.sys does the job of disk.sys in
the case of mpio.
That’s why I am expecting mpdev.sys to handle the job
IRP_MJ_READ and IRP_MJ_WRITE.

Thanks
Ramesh
----- Original Message -----
From: “Mark Roddy”
> To: “Windows System Software Devs Interest List”
> Subject: RE: [ntdev] Multipath IO: IRP_MJ_READ and IRP_MJ_WRITE
> Date: Thu, 27 Jan 2005 07:22:07 -0500
>
> >
> > Below disk.sys IO uses IRP_MJ_SCSI. Read the disk.sys
> source code, it
> > is in the ddk.
> >
> > =====================
> > Mark Roddy
> > Windows .NET/XP/2000 Consulting
> > Hollis Technology Solutions 603-321-1032 www.hollistech.com
> >
> > > -----Original Message-----
> > > From: xxxxx@lists.osr.com
> > > [mailto:xxxxx@lists.osr.com] On Behalf Of Ramesh K
> > > Sent: Thursday, January 27, 2005 2:46 AM
> > > To: Windows System Software Devs Interest List
> > > Subject: [ntdev] Multipath IO: IRP_MJ_READ and IRP_MJ_WRITE
> > >
> > > Hi All,
> > >
> > > I am working on a DSM driver and have a basic query on it.
> > >
> > > Will the IRP_MJ_READ and IRP_MJ_WRITE pass through the
> mpio drivers or not?
> > > When I tested with the sample DSM and found that the
> IRP_MJ_READ and
> > > IRP_MJ_WRITE are not passed through any of the MPIO driver files
> > > (mpspfltr.sys, mpdev.sys and mpio.sys) but it is handled by the
> > > disk.sys and ntfs.sys.
> > >
> > > When I checked with the “Device Tree” the mpdev.sys is not
> > > installed at all. It would be of great help, if anyone
> can tell the
> > > expected behavior in a final setup. I feel there is some
> problem in
> > > this behavior, since the mpdev.sys should replace the disk.sys
> > > functionality. Is my assumption correct or not?
> > >
> > > Any comments would be of great help.
> > >
> > > Thanks in advance
> > >
> > > Ramesh
> > >
> > >
> > > –
> > >
> > > Find what you are looking for with the Lycos Yellow Pages
> > > http://r.lycos.com/r/yp_emailfooter/http://yellowpages.lycos.c
> > > om/default.asp?SRC=lycos10
> > >
> > >
> > > —
> > > Questions? First check the Kernel Driver FAQ at
> > > http://www.osronline.com/article.cfm?id=256
> > >
> > > You are currently subscribed to ntdev as: unknown lmsubst
> tag argument: ‘’
> > > To unsubscribe send a blank email to
> xxxxx@lists.osr.com
> > >
> >
> >
> >
> >
> > —
> > Questions? First check the Kernel Driver FAQ at
> > http://www.osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as: xxxxx@lycos.com To
> > unsubscribe send a blank email to xxxxx@lists.osr.com
>
> –
>

> Find what you are looking for with the Lycos Yellow Pages
> http://r.lycos.com/r/yp_emailfooter/http://yellowpages.lycos.c
> om/default.asp?SRC=lycos10
>
>
> —
> Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: unknown lmsubst tag
> argument: ‘’
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>