All of my imovie events are stored on an external hard drive. How do I backup this external hard drive? If the external hard drive crashes, how do retrieve the imovie events?

Question

I have all of my imovie events stored on an external hard drive in order to save space on my MacBook Pro's internal drive.  I currently back up both my MacBook Pro and the external hard drive  using a second external hard drive via Time Machine. I have a few questions:
1. How can I be sure that the external drive is actually being backed up.
2. How do I retrieve the imovie events if the 1st external hard drive crashes?
Thank for your help!

Answer 1

Let me give you some thoughts. I can tell you my plan, but ultimately you will need your own plan that makes sense for you.
I do not think that your idea of having two separate Time Machine destinations will work. You can have two external drives as Time Machine volumes, but they will both back up the same data set. You cannot dedicate one to iMovie and one to everything else. They will both have everything, so you may still have a space problem.
One way to overcome this is to back up the iMovie volume by using a tool like SuperDuper! or Carbon Copy Cloner. The good news is that your Event files should be pretty stable and there is no need to back them up every 15 minutes. So something like SuperDuper, which you can set to automatically backup once a day, for example, is probably fine. I am pretty sure that this would work if you kept the Projects on the same external drive. As long as Projects and Events are on the same drive, then the cloning stragy should work (but you should always test.)
Because projects change more often than events, and projects can become corrupted, I would definitely back up the Project Library to Time Machine. You can do this even though it is on an external drive. (And even though you may be periodically backing up the entire drive that contains the projects.)
Here are some thoughts on how I approach backup, copied from an earlier answer...
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Great question. I think the issue of backup is a important one, and one I always worry about since I have a lot of video footage that is irreplaceable.
For back-up, it is helpful to define the risk you are trying to protect from.
For example,
1) risk of corruption in iMovie --> I  use Time Machine
2) risk of hard drive failure --> I use SuperDuper! nightly for bootable backup) and Time Machine all the time
3) Risk of theft or fire --> offsite backup
Here is what I do...
1) I back up my boot disk with SuperDuper automatically each night so I always have a bootable system.
2) I back up my original video files. For my Motion JPEG, VHS-->AIC, DV, and 8MM to DV, the EVENT is the copy I back up. (I keep the tapes, but I never want to have to import the tapes again.)
For my AVCHD high def video, I back up the camera archive of the AVCHD, but I am not currently backing up the Event files, because I would need from 4 to 8 TB to back up these events depending on whether I made one copy or two. I can always re-create the Event from the camera archive.
3) I use CrashPlan for my offsite backup. It costs less than $4 per month, and I seeded the initial backup to an external drive to minimize having to transfer video files over the Internet. I currently have over 2TB of data backed up to CrashPlan, which includes my entire boot drive, and the files described in #2.
4) All of the above is automated, so I don't have to think about it too much. If I have to manually do stuff, I tend to get behind.
You have to consider the value of total multiple redundancy vs. the likelihood that 2 or three unlikely events would all happen at once. For example, CrashPlan could lose my data. My hard disk could fail. I could lose everything in a fire. But it is unlikely that they would all happen at once, except in nuclear war, in which case, who cares?