Volume Snapshots..

Hi,
Could any body shed some light on inner workings of Volume Snapshot driver
volsnap.sys.

I belive it sits above the Disk Class Driver and Duplications Disk level
Io.Are there some good articles which explain how the storage stack looks
like and works when volsnap is enabled on the system.

Regards
Subodh

Mark
Mon Dec 06 06:06:06 CST 2004

Subodh Radheshyam Gupta wrote:
> Hi,
> Could any body shed some light on inner workings of Volume Snapshot driver
> volsnap.sys.
>
> I belive it sits above the Disk Class Driver and Duplications Disk level
> Io.Are there some good articles which explain how the storage stack looks
> like and works when volsnap is enabled on the system.
>
> Regards
> Subodh
>
volsnap sits above volumes. Anything that declares itself to be the pnp
string Storage\Volume gets its device object attached by volsnap.

There is "Inside Windows Storage: Server Storage Technologies for
Windows 2000, Windows Server 2003, and Beyond", Dilip C Naik,
Addison-Wesley 2003. I've never read it. It has at least one chapter on
the driver architecture.

--

=====================
Mark Roddy DDK MVP
Windows 2003/XP/2000 Consulting
Hollis Technology Solutions 603-321-1032

Maxim
Mon Dec 06 07:48:34 CST 2004

It sits between the Volume Manager (FtDisk or DmIo) and the FSD.
IOCTL API to it is undocumented, and the VSS COM-based API is the only mean
to acces it.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

"Subodh Radheshyam Gupta" <SubodhRadheshyamGupta@discussions.microsoft.com>
wrote in message news:7AA35AD9-2DCF-4AAD-8667-55102896196C@microsoft.com...
> Hi,
> Could any body shed some light on inner workings of Volume Snapshot driver
> volsnap.sys.
>
> I belive it sits above the Disk Class Driver and Duplications Disk level
> Io.Are there some good articles which explain how the storage stack looks
> like and works when volsnap is enabled on the system.
>
> Regards
> Subodh
>

SubodhRadheshyamGupta
Tue Dec 07 06:05:02 CST 2004

Hi Max / Mark,
Thanks for nice explanation.
I did some digging on my Xp pro which has fix IDE disk.My Storage stack
looks like this -
The shape of stack is something like this (atleast on my system) -

Io Subsystem
|
|
File System (legacy ntfs.sys)
|
|
Volume Snapshot Service (legacy volsnap.sys)
|
|
Volume Manager (legacy dmio.sys and ftdisk.sys)
|
|
Partition Manager (legacy partmgr.sys)
|
|
Disk Class Driver (WDM disk.sys)
|
|
Port Driver + Miniport Driver (WDM / legacy)
|
|
Bus Driver (WDM atapi.sys)

Is my observation correct or i am forgetting some other driver in this stack
??

what happens when a cluster is configured ? what will change in the stack
then ?

Regards
Subodh


"Maxim S. Shatskih" wrote:

> It sits between the Volume Manager (FtDisk or DmIo) and the FSD.
> IOCTL API to it is undocumented, and the VSS COM-based API is the only mean
> to acces it.
>
> --
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> maxim@storagecraft.com
> http://www.storagecraft.com
>
> "Subodh Radheshyam Gupta" <SubodhRadheshyamGupta@discussions.microsoft.com>
> wrote in message news:7AA35AD9-2DCF-4AAD-8667-55102896196C@microsoft.com...
> > Hi,
> > Could any body shed some light on inner workings of Volume Snapshot driver
> > volsnap.sys.
> >
> > I belive it sits above the Disk Class Driver and Duplications Disk level
> > Io.Are there some good articles which explain how the storage stack looks
> > like and works when volsnap is enabled on the system.
> >
> > Regards
> > Subodh
> >
>
>
>

Maxim
Tue Dec 07 07:22:05 CST 2004

The stack is correct, the only mistake is that ATAPI is a storage port
driver.

On a cluster, CLUSDISK inserts itself to the same location as VolSnap -
above the volume manager.

Also Kaspersky antivirus puts its driver to the same location. :)

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

"Subodh Radheshyam Gupta" <SubodhRadheshyamGupta@discussions.microsoft.com>
wrote in message news:8D69EA25-AC1E-491B-A16F-9DAFFC2630E2@microsoft.com...
> Hi Max / Mark,
> Thanks for nice explanation.
> I did some digging on my Xp pro which has fix IDE disk.My Storage stack
> looks like this -
> The shape of stack is something like this (atleast on my system) -
>
> Io Subsystem
> |
> |
> File System (legacy ntfs.sys)
> |
> |
> Volume Snapshot Service (legacy volsnap.sys)
> |
> |
> Volume Manager (legacy dmio.sys and ftdisk.sys)
> |
> |
> Partition Manager (legacy partmgr.sys)
> |
> |
> Disk Class Driver (WDM disk.sys)
> |
> |
> Port Driver + Miniport Driver (WDM / legacy)
> |
> |
> Bus Driver (WDM atapi.sys)
>
> Is my observation correct or i am forgetting some other driver in this stack
> ??
>
> what happens when a cluster is configured ? what will change in the stack
> then ?
>
> Regards
> Subodh
>
>
> "Maxim S. Shatskih" wrote:
>
> > It sits between the Volume Manager (FtDisk or DmIo) and the FSD.
> > IOCTL API to it is undocumented, and the VSS COM-based API is the only
mean
> > to acces it.
> >
> > --
> > Maxim Shatskih, Windows DDK MVP
> > StorageCraft Corporation
> > maxim@storagecraft.com
> > http://www.storagecraft.com
> >
> > "Subodh Radheshyam Gupta" <SubodhRadheshyamGupta@discussions.microsoft.com>
> > wrote in message news:7AA35AD9-2DCF-4AAD-8667-55102896196C@microsoft.com...
> > > Hi,
> > > Could any body shed some light on inner workings of Volume Snapshot
driver
> > > volsnap.sys.
> > >
> > > I belive it sits above the Disk Class Driver and Duplications Disk level
> > > Io.Are there some good articles which explain how the storage stack looks
> > > like and works when volsnap is enabled on the system.
> > >
> > > Regards
> > > Subodh
> > >
> >
> >
> >

Mark
Tue Dec 07 19:28:52 CST 2004

Maxim S. Shatskih wrote:
> The stack is correct, the only mistake is that ATAPI is a storage port
> driver.
>
> On a cluster, CLUSDISK inserts itself to the same location as VolSnap -
> above the volume manager.
>
> Also Kaspersky antivirus puts its driver to the same location. :)
>
And of course you can have arbitrary filter drivers at any point or
various virtual storage technology like MPIO below disk.sys. But the
stack is an accurate representation of the basic functionality.

--

=====================
Mark Roddy DDK MVP
Windows 2003/XP/2000 Consulting
Hollis Technology Solutions 603-321-1032

SubodhRadheshyamGupta
Thu Dec 09 04:53:01 CST 2004

Thanks Mark / Max,

Could you please point some nice article which demonstrates volume monunting
unmointing process ? DDK mentions several IOCTLs which are sent and recieved
between Volume Manager ,Mount Manager and Their Clients ...

What are these clients ? User mode APis ? which drivers are involved in the
stack above and how they talk to each other ?

My Aim is to mount a volume in kernel mode how can i do it ?

Subodh


"Mark Roddy" wrote:

> Maxim S. Shatskih wrote:
> > The stack is correct, the only mistake is that ATAPI is a storage port
> > driver.
> >
> > On a cluster, CLUSDISK inserts itself to the same location as VolSnap -
> > above the volume manager.
> >
> > Also Kaspersky antivirus puts its driver to the same location. :)
> >
> And of course you can have arbitrary filter drivers at any point or
> various virtual storage technology like MPIO below disk.sys. But the
> stack is an accurate representation of the basic functionality.
>
> --
>
> =====================
> Mark Roddy DDK MVP
> Windows 2003/XP/2000 Consulting
> Hollis Technology Solutions 603-321-1032
>