can't open /dev/sda3 exclusively

Hi, please help!!!

I'm installing an openSUSE 10.3 into a computer, after creating the following partitions:

Primay Partition
swap
/
LVM(volume manager) - /dev/sda3
/opt, /var, /tmp, /usr, /local

when i tried to continue installing, after creating the partitions
i am prompted with the following failure:

You may have to refer to it by the /dev/mapper entry. Are you doing this on the CL or in Yast?
Also, just an aside, but why are you not putting / in the LVM? You can carve out a 90MB /boot and keep the rest maintained by LVM, including swap, or, with recent improvements in speed, put swap on a mounted filesystem as a file, as it will continue to do block I/O to the file.

got ya, I'll try this out.