I have been having a very difficult time correlating physical addresses to LVM2/DM addresses. for instance, if i do: dmsetup table /dev/mapper/avtest-vdisk2g the result is: 0 4194304 linear 22:65 384 from what i currently understand, this means logical extent 0 (which is composed of 8192 512 byte sectors in the default config) of this LV should start at physical sector 384 of device 22:65 (/dev/hdd1 on my machine) after i've written to the logical device a couple times, it appears this correlation doesn't hold when i access the physical sectors on hdd1 using dd. however, if i use dd to access the sectors through the LV, all the data appears as it should. i was under the impression that the logical to physical mappings was quite straightforward and intuitive, but i feel that i am missing some key information. Can someone help me out of is there decent developer documentation somewhere that explains the mappings? As a more complete example of my problem, if i do the following: dd if=/dev/zero of=/dev/avtest/vdisk2g count=1 then do: dd if=/dev/avtest/vdisk2g of=tmpfile.out count=1 then tmpfile.out contains 512 bytes of zeros. however, if I do: dd if=/dev/hdd1 of=tmpfile.out skip=384 count=1 then tmpfile.out contains other data, not the zero's i would expect from the output of the dmsetup table command above. I feel i'm missing something fairly basic here, but I haven't had any luck tracking this relationship down. I suppose there is always the sourc code :) Thanks a lot. _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
