In addition to daily backups to protect work in progress, you should also be doing long term archiving of all your images and critical files. Unlike daily backups where you can access your backed up data quickly because it is plugged in to your computer, if you don't break your backups up, your backup system can be unwieldy if you are making it search and update 2TB of data every day.How often you should perform long term archiving depends upon how many photos you shoot and how much space you are taking up on your hard drives.
I tend do to do archiving once a month. Doing it monthly keeps the number of images manageable and while I am archiving, I also compile everything for quarterly copyright sumbisison. I look through the images, delete anything that there is no use for (out of focus, mis-fires, etc.) and I burn everything else (from the raw shoots) to two DVD's (two copies of the same images.)
I also use a program called CD Finder to catalog all of the DVD's that I've burned so that I can search for photos using the database it builds. It is just another way to keep track of images.
One set of DVD's is stored on-site in my office closet in an acid-free box designed for the storage of CD's and DVD's. The other set of DVD's is stored off-site in a similar set of boxes. Both sets are stored in a cool, dark and dry location that isn't prone to big shifts in temperature or humidity.
After I burn the two DVD's, I move the files over to a hard drive that is only used for archiving. At the end of the year, I duplicate the hard drive (two copies of the same data) and put one hard drive in my safe deposit box at my bank, and the other with my off-site set of DVD's.
At the end of the year, I also burn DVD's and copy to the hard drive(s) all of my published images from the year, clips, copies of everything submitted for copyright (and copies of the submitted thumbnails) and anything else photo related that would fall within the year.
I reason I archive to hard drives as well as DVD's is because it is much easier to manage the data on a hard drive. If all of the data on my RAID got corrupted, it would be much easier to restore it from a few hard drive than from hundreds of DVD's that would have to be read one at a time.
The reason I archive to DVD's is because they are cost effective and allow me to do incremental archiving of images in smaller batches that I can then move to my off-site more quickly instead of waiting until the end of the year to distribute my backups.
There is still some debate about the lifetime of DVD's. If you burn quality disks, and verify the data, you should be in good shape. Most disks that go "bad" are bad because of scratches or they were left in the sun, or some other environmental cause.
You should store your archive DVD's in good hard cases (DVD's can get scratched in those cheap little paper sleeves) and use CD safe pens to write on them. You should store them in some sort of container designed for storing disks and keep them in a dry, dark, cool place. This will help extend the life considerably.
I figure that before I get close to the lifespan of a DVD, we will be archiving on something with 10 times the capacity... look at the transition from CD's to DVD's. So I am not fretting over the lifetime of the DVD's.
I would also advise that you not store your original files and all of your backups in the same place. Living in San Diego, wildfires are a constant threat, and there were a number of photographers that not only suffered the loss of their homes during the fires, but also lost all their photos and backups because they were all stored on-site. Spread your backups out so that if something catastrophic happens, you have other backups to rely on that are kept in other places.
You can even partner with another photographer to keep a copy of their backups and in exchange they store a copy of your backups.
The other thing that I use (and really love) as part of my archiving strategy is an external RAID where I also store every digital photo I've ever shot and all of my scanned film images, too. I use a Firmtek 4 bay RAID which I've been really happy with. I have 750GB drives in mine, and I am not sure I could live without it now.The ability to have instant access to every image I've ever shot without even getting up from my chair is awesome. It has saved me hours of time that I used to spend pulling archived DVD's, getting the images off of them and then refiling them every time I had a photo request from a client. Using a RAID also reduces the risk of damaging your archive DVD's. Since the RAID is plugged into your computer, Spotlight catalogs the disks which makes it really easy to search for images.
Another advantage of using a RAID is that you can mirror the drives. Just like the name implies, one drives is a mirror image of the other. When you add or subtract files, those changes are made on both drives at the same time. When one of the drives in the mirror fails, you can pop in a new drive and the RAID will copy all the data back over to the new drive and you have no down time.
I use SoftRAID to run my Firmtek box (vs. Apple's built in RAID control.) It gives me more flexibility in how I set things up, and also gives you warnings if there are any problems with the disks in the RAID.
RAID is not a replacement for good archival backups, however. The problem with using a RAID is that if the data becomes corrupt or gets deleted, that change will be on both the original disk and the mirror (since they are the same) so having other good backups is critical. The mirroring is only protection against hardware failure, not data corruption.
Now is a great time to come up with your own archiving plan and start backing things up.
