I'm trying to do some file system checks using LVM snapshots of our Logical Volumes to see if any of them have dirty file systems.

The problem that I have is that our LVM only has one Volume Group with no available space. I was able to do fsck's on some of the logical volumes using a loopback file system. However my question is, is it possible to create a 200GB loopback file system, and saved it on the same partition/logical volume that I'll be taking a snapshot of? Is LVM smart enough to not take a snapshot copy of the actual snapshot?

[root@server z]# vgdisplay
--- Volume group ---
VG Name               Web2-Vol
System ID
Format                lvm2
Metadata Areas        1
Metadata Sequence No  29
VG Access             read/write
VG Status             resizable
MAX LV                0
Cur LV                6
Open LV               6
Max PV                0
Cur PV                1
Act PV                1
VG Size               544.73 GB
PE Size               4.00 MB
Total PE              139450
Alloc PE / Size       139450 / 544.73 GB
Free  PE / Size       0 / 0
VG UUID               BrVwNz-h1IO-ZETA-MeIf-1yq7-fHpn-fwMTcV


[root@server z]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2             9.7G  3.6G  5.6G  40% /
/dev/sda1             251M   29M  210M  12% /boot
/dev/mapper/Web2--Vol-var
                       12G  1.1G   11G  10% /var
/dev/mapper/Web2--Vol-var--spool
                   12G  184M   12G   2% /var/spool
/dev/mapper/Web2--Vol-var--lib--mysql
                   30G   15G   14G  52% /var/lib/mysql
/dev/mapper/Web2--Vol-usr
                   13G  3.3G  8.9G  27% /usr
/dev/mapper/Web2--Vol-z
                  468G  197G  267G  43% /z
/dev/mapper/Web2--Vol-tmp
                  3.0G   76M  2.8G   3% /tmp
tmpfs                 7.9G   92K  7.9G   1% /dev/shm

The logical volume in question is /dev/mapper/Web2--Vol-z. I'm afraid if I created the loopback file system in /dev/mapper/Web2--Vol-z and take a snapshot of it, the disk size will be trippled in size, thus running out of disk space available.