Intercept write to disk

Intercept write to disk

[Mishael A Sibiryakov]

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Hi.

Probably i have a stupid question but i can't find adequate solution for
it. I want to intercept write to real disk partition or entire disk
(except of swap partition of course). As i understood vfs and Co i think
that i need to work on level between fs driver and disk driver. But it's
unclean for me. Please tell me is it possible and if possible then say
how or put me to some documentation.

I need a offset from start or CHS value with buffer for save it.

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Re: Intercept write to disk

[Bernd Eckenfels]

Mishael A Sibiryakov <death@junki.org> wrote:
> Probably i have a stupid question but i can't find adequate solution for
> it. I want to intercept write to real disk partition or entire disk
> (except of swap partition of course). As i understood vfs and Co i think
> that i need to work on level between fs driver and disk driver. But it's
> unclean for me. Please tell me is it possible and if possible then say
> how or put me to some documentation.

You can write a devmapper module, or maybe pre-load a shared user mode
library.

Gruss
Bernd

Re: Intercept write to disk

[Mishael A Sibiryakov]

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On Fri, 2006-05-26 at 23:21 +0200, Bernd Eckenfels wrote:
> Mishael A Sibiryakov <death@junki.org> wrote:
> > Probably i have a stupid question but i can't find adequate solution for
> > it. I want to intercept write to real disk partition or entire disk
> > (except of swap partition of course). As i understood vfs and Co i think
> > that i need to work on level between fs driver and disk driver. But it's
> > unclean for me. Please tell me is it possible and if possible then say
> > how or put me to some documentation.
> 
> You can write a devmapper module, or maybe pre-load a shared user mode
> library.

Hm, i need a somthing transparent, this tool is for make image of entire
disk/partition on fly. Because tool is get some time for work i need to
store changes between start and end of the process for append it to
image. Probably i thinking in wrong way and i need a something else.

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Re: Intercept write to disk

[Michael Raskin]

Mishael A Sibiryakov wrote:
> Hm, i need a somthing transparent, this tool is for make image of entire
> disk/partition on fly. Because tool is get some time for work i need to
> store changes between start and end of the process for append it to
> image. Probably i thinking in wrong way and i need a something else.

Maybe you want to back up a partition as it was at some moment in the 
past (exactly)? Then you have to make a device-mapper-snapshot out of 
it. You  need to install device-mapper module and userspace tools, and 
make the following:  original device is never used directly; instead a 
snapshot-origin mapping is made of it and is always used. When you need 
snapshot, you create a file (on another partition, of course; maybe even 
in the memory if you are sure you will do everything quickly enough), 
make it a loopback device, and make a snapshot out of snapshot-origin 
you have and this loopback for changes rollback. Maybe it is also better 
  to mount -o remount,sync the device for the time of creating snapshot 
device in order to have less problems with consistency. And remount it 
back when you start copying.