It's a good question and one that I've struggled with. Here's what I'm doing now, which seems to be (knock wood) working fairly well...
I shoot RAW exclusively. (See my RAW workflow for sports shooters
here.) I download my cards to my 1.1TB RAID5 using Breeze Downloader Pro to automatically-created folders, named for date and a short job description (e.g., 070909 AYSA19g for Atlanta Youth Soccer U-19 girls on Sept 9). At the same time, DL Pro automatically copies a second duplicate to one of my several Seagate external firewire drives.
I have my system configured to backup nightly to another external drive. So, as soon as I download I have two copies, and by the next morning I have three.
When I process a session I delete all the non-keepers. Delete means delete — they're gone — except, I still have the backups. Periodically I (a) roll off old auto backups on the first external drive, to free up space, and (b) reconcile the backups on the second disk so that what is backed up long term ends up being the edited/selected sessions, keepers only, rather than everything. But this is only every few weeks/months.
When I process, I convert the RAW files to TIFs with Capture One and then produce the HTML galleries with BreezeBrowser Pro. Then I delete the processed TIFs, keeping only the original RAW files plus the CO settings to produce the processed file again quickly for print orders.
Also periodically, I backup the backups to yet another set of external drives that otherwise stay offsite at my neighbor's house.
What this amounts to, when all is said and done, is that I have ALL my files, going back five years or so, live and instantly available on my RAID5, I have them all backed up, online, to external drives, and backed up again, offline and offsite. They're arranged in rough categories — e.g., Soccer 2007 — and between that, the folder names, and my file naming convention which is similar, I can generally find things pretty quickly.
I have over 50,000 images on my website, and at least a couple of times a year I'll get print orders going back two or three or even occasionally four or more years.
I experimented for a while with DVD storage but it was just too unwieldy for my volume of images. And the idea of having to actually do a restore of all that data from DVD (or worse yet, some sort of internet storage) was too awful to contemplate.
My website is backed up similarly and, after a very bad and educational experience recently, so are my system/application drives. But no system is perfect, and I'm sure I'll find new and interesting ways to screw up using this one.
Nill
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www.toulme.net