Relationship between Device Mapper and LVM2

Dear Sir,
We are trying to do some work on LVM2, by trying to make it more
dynamic and suitable for virtual machines. We have a very fundamental doubt as follows:

Is LVM2 based on top of "device mapper" and uses "device mapper" as the underlying layer of support for writing /reading on the disk. Or Device mapper is placed between the kernel and the LVM2. Aslo if possible please tell us the entry point of kernel into the device mapper.

Any suggestions on this topic will be highly appreciated.

Thanks,
Vivek

http://people.redhat.com/agk/talks/FOSDEM_2005/

esp. http://people.redhat.com/agk/talks/FOSDEM_2005/img3.gif

      http://people.redhat.com/agk/talks/FOSDEM_2005/img4.gif

Alasdair

[email protected]

Dear Sir,
Thanks a lot for your timely response. It has helped us a lot.
Just one last query. When a user program issues a read command from a file residing on a logical volume, how does the call actually gets mapped onto the hard disk. We believe that the kernel passes the "generic" command to the device mapper which then makes the final translation on the basis of mapping tables stored with it. We just wanted to be sure that LVM2 code does figure in the translation of the read requests from the user applications to the disk.

Thanking you in advance,
Vivek