diff --git a/snapshot-rootfs.sh b/snapshot-rootfs.sh
index 7ec50b3..afaae0b 100755
--- a/snapshot-rootfs.sh
+++ b/snapshot-rootfs.sh
@@ -1,8 +1,36 @@
 #!/usr/bin/bash
+# snapshot-rootfs.sh
+# 
+# In your /etc/profile, export the following variables
+# LVM_VG_ROOTFS=vg0
+# LVM_LG_ROOTFS_NAME=rootfs-arch
+# LVM_ROOTFS_SNAPSHOT_SZ=10G
+source /etc/profile
+
+crash() {
+    echo $1;
+    exit 1;
+}
+
+[ \
+  -n "$LVM_VG_ROOTFS" \
+  -a -n "$LVM_LG_ROOTFS_NAME" \
+  -a -n "$LVM_ROOTFS_SNAPSHOT_SZ" \
+] || crash "Missing one of the LVM variables for snapshot-rootfs.sh";
 
-VG=vg0
-ROOTFS=rootfs-arch
-SZ=10G
 DATE=`date +%Y%m%dT%H%M`
 
-lvcreate -n $ROOTFS-$DATE --snapshot -L $SZ $VG/$ROOTFS
+LAST_SNAPSHOT_NAME=`lvs --select "origin = $LVM_LG_ROOTFS_NAME" \
+  --noheadings -o "data_percent,lv_name" 2>&1 \
+  |sort -n|grep -o '[^[:space:]]\+$'`
+
+echo "The last snapshot's name is : $LAST_SNAPSHOT_NAME. Remove it? (y/n)"
+
+read REMOVE_LAST_SNAPSHOT
+
+[ $REMOVE_LAST_SNAPSHOT = "y" ] && lvremove $LVM_VG_ROOTFS/$LAST_SNAPSHOT_NAME
+
+lvcreate -n $LVM_LG_ROOTFS_NAME-$DATE \
+  --snapshot \
+  -L $LVM_ROOTFS_SNAPSHOT_SZ $LVM_VG_ROOTFS/$LVM_LG_ROOTFS_NAME
+