I've got an LVM partition /dev/sda4, in it there is a "system" group. Disconnected the hard drive, connected it to another PC and system do not see this LVM. Well it was seen like /dev/sda4 (type LVM), inside "system" free space.
Returned to the original PC - same result
The problem is that there is a valuable info there and I don't know how to restore it now