1) Turn Legacy Backups (e.g. tar and rsync) into Online Backups

Take a Hot Copy of your disk before starting your tar or rsync backup.  Backing up your Hot Copy will turn your tar backups into consistent point-in-time online backups.
# hcp /dev/sda3
# tar -cvzpflS /var/hotcopy/sda3

2) Take a Hot Copy before running Scripts - No More Ahhh I didn't mean to rm -Rf that!

Need to run a script that deletes a bunch of files?  Changes permissions all over the place?  Take a Hot Copy first!  Make a mistake...?  No problem.  You have an instant point-in-time backup!
# hcp --read-only /dev/sda3
# RUN DANGEROUS SCRIPT or COMMAND

3) Use Hot Copy to Test Dangerous Scripts or Commands

Want to test that Perl script out before running it on your system?  Want to run that strange shell script and worried it's an exploit?  Run it inside of a Hot Copy!
# hcp --read-only /dev/sda3
# chroot /var/hotcopy/sda3
# RUN DANGEROUS SCRIPT or COMMAND

4) Run fsck Safely While Your File System is Mounted

Want to know if your file system is corrupt without shutting down your server? 

Make a Hot Copy of the device (yes even while the system is running).  Now you have a consistent point-in-time snapshot you can run fsck on to see if you have problems.  Now remember Hot Copies are lost when you reboot so you can’t use fsck to fix the errors.  You can use it to detect errors without shutting down.  This way you can know that when you reboot you will be stuck in fsck for hours and it won’t be a surprise

# hcp --skip-mount /dev/sda3
# fsck -a -y /dev/hcp1

5) See what files change on your system

Take a Hot Copy before making a change to your system.  Then use the diff utility to tell you what files changed between your Hot Copy and the real device.

Let’s say you have your root file system (/) on device /dev/sda3

Now take a Hot Copy
# hcp /dev/sda3

Now make some changes
# ./run-some-installer.sh

See the differences
# diff --recursive / /var/hotcopy/sda3