[root@kmsan02 mapper]# vgchange -a n backup
  0 logical volume(s) in volume group "backup" now active
[root@kmsan02 mapper]# vgchange -a y backup
  device-mapper: reload ioctl failed: Invalid argument
  1 logical volume(s) in volume group "backup" now active


Also receive this when trying to use /dev/mapper/vgname-lvname 

[root@kmsan02 mapper]# mke2fs -j ./backup-befull
mke2fs 1.35 (28-Feb-2004)
mke2fs: Device size reported to be zero.  Invalid partition specified, or
        partition table wasn't reread after running fdisk, due to
        a modified partition being busy and in use.  You may need to reboot
        to re-read your partition table.