I am not an expert on filter and other Windows drivers, but basically a 
filter driver is a piece of software that runs in kernel (privileged) 
mode, so it has access to the system memory and hardware. It gets its name 
because it "filters" (intercepts and manipulates) I/O requests. For 
example, antivirus scanners are typically implemented as a filter driver, 
as is the TSM LVSA which is used for online image and OFS backups. CDP is 
implemented as a filter driver to detect I/O requests, which is how it 
figures out that files are changing.

I think I got that right...   :-)

Regards,

Andy

Andy Raibeck
IBM Software Group
Tivoli Storage Manager Client Development
Internal Notes e-mail: Andrew Raibeck/Tucson/IBM@IBMUS
Internet e-mail: storman AT us.ibm DOT com

IBM Tivoli Storage Manager support web page: 
http://www-306.ibm.com/software/sysmgmt/products/support/IBMTivoliStorageManager.html

The only dumb question is the one that goes unasked.
The command line is your friend.
"Good enough" is the enemy of excellence.

"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 2005-10-05 
09:14:18:

> 
> > Actually, it is my understanding that CDP does *not* use the same 
Windows
> > API function (ReadDirectoryChangesW) that JBB uses. Rather, it is a 
kernel
> > filter.
> 
> I stand corrected - now I've just gotta go and figure out what a 
> kernel filter is (that'll be a different mailing list I'm sure)... 
> 
> :o) 
> 
> David McClelland 
> Storage and Systems Management Specialist 
> IBM Tivoli Certified Deployment Professional (ITSM 5.2) 
> SSO UK Service Delivery ? Storage Services 
> IBM Global Services ? IBM United Kingdom 
> 
> [image removed] 
> 
> 
> 
> 

> 
> Andrew Raibeck <storman AT us.ibm DOT com> 
> Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> 
> 05/10/2005 16:33 
> 
> Please respond to
> "ADSM: Dist Stor Manager"
> 
> To
> 
> ADSM-L AT VM.MARIST DOT EDU 
> 
> cc
> 
> Subject
> 
> Re: [ADSM-L] Tivoli Continuous Data Protection for Files
> 
> 
> 
> 
> > CDP sits on top of the same Win32 API that the TSM Journal engine
> > does
> 
> Actually, it is my understanding that CDP does *not* use the same 
Windows
> API function (ReadDirectoryChangesW) that JBB uses. Rather, it is a 
kernel
> filter.
> 
> Andy Raibeck
> IBM Software Group
> Tivoli Storage Manager Client Development
> Internal Notes e-mail: Andrew Raibeck/Tucson/IBM@IBMUS
> Internet e-mail: storman AT us.ibm DOT com
> 
> IBM Tivoli Storage Manager support web page:
> http://www-306.ibm.
> com/software/sysmgmt/products/support/IBMTivoliStorageManager.html
> 
> The only dumb question is the one that goes unasked.
> The command line is your friend.
> "Good enough" is the enemy of excellence.