While you trying to vary on a volume group or mount some filesystem to consist of this error code:
0516-082 varyonvg: Unable to access a special device file.
Execute redefinevg and synclvodm to build correct environment.
mount: 0506-324 Cannot mount /dev/oradata_lv on /oradata: There is a request to a device or address that does not exist.
make the following steps:
redefinevg -d hdisk2 vgname
synclvodm -v vgname