Not strictly part of my photography this topic, but I think it's worth a quick read to get you up to speed on how to safeguard effectively your digital wedding deliverables and what are the best practices to prevent any loss of your precious data that you wouldn't dare to lose.
If you work with IT technology or computers are an integral part of your life, you probably heard of the importance of making backups of your files, save your work progress fanatically, etc. But even if these don't apply to you, you surely have some good memories stored in a digital format. Digital backups are basically copies of your files, stored in a secure place, preferably away from your original in use. Therefore a backup is always off the computer (phone, tablet, etc.), because if the device fails for any reason - and they do fail, the only question is when -, your backup should be still safe and sound.
Now you don't want to lose half an hour of your work because the computer just froze, do you?
But the same principle applies to any person or family, even if they don't really think much about their digital life, the same regime of making backups should be followed. Either way there're most likely photos at least on your phone you made of your children, your dog, your better half, etc. Would you dare to lose those files? Just because your phone died and it can't be recovered?
Your family album on your phone you collected in the last few years? The work files on the computer your livelihood depends on? Your music collection you carefully curated over the last decade? E-books that would be very hard to acquire again? Perhaps your wedding photos that you spent a small fortune on at a once in a life occasion? :)
No digital data lasts forever, at least not the media they are on. Unfortunately we don't have the technology currently that is 100% reliable, so there's no guarantee that your data will be retained on any commercially available medium, but we have good backup and archival strategies to mitigate the problem and prevent any data loss.
There's one approach widely used in the IT industry and considered the best practice among experts: the so called 3-2-1 backup strategy.
At least 3 copies, on 2 types of media and 1 copy 'off-site'.
For the average user this means that you should make at least two backups of the original, both are stored off the computer (or any device the primary copy is on) and shouldn't be the same kind of device, let alone the same type of anything - like two identical HDDs, or the same brand/batch of discs, etc. because we don't want them to fail around at the same age. Different kind of mediums have different lifespans.
And then you may want to keep one copy off-site, somewhere far away from your computer or your home for that matter. If your computer crashes, you may have one backup at hand on an external hard drive - disconnected normally (everything connected to your computer is considered "on" your computer, so it's not a backup nor safe). But imagine if your home is hit by a disaster, chances are that would wipe out not just the computer but the external hard drive too. So your third copy should be far far away, ideally not even in the same country. If that's not feasible then at least a few counties away to protect from natural disasters, etc. Perhaps at your parents?
Storage Medium Recommendations
All storage type is prone to lose its data over time due to data decay. The lifespan of a particular type of media may differ though before this happens.
For example data retention on any HDD is considered to be around 5-8 years before it starts to lose its data due to magnetic field-strength degradation. Although it's kinda cheap and cost effective and currently the most commonly used media. It's prone to mechanical failures that can happen anytime, but most likely in the first few months if there's a QC problem, or when they get considerably old. This means they can just fail even if you haven't exposed them to any mechanical shocks. So never use a brand new HDD for offline backups, but only those that have been tested and worked flawlessly for some time and safe to say they don't carry manufacturing defects.
External Hard Drive
Same problems like above, as in the enclosure you find a conventional HDD.
But on top of all that the external hard drives tend to develop a malfunction in the USB interface, but most of the time the actual HDD inside the case isn't faulty. Don't be too quick to ditch the whole drive, as we already fill our landfills with perfectly good HDDs because of faulty enclosures and cheap USB-Sata interfaces.
These aren't considered very reliable, mostly because their questionable quality from questionable sources. So shouldn't be used as a permanent solution or for archiving at all. Also prone to bit rotting because of electron leaking in the memory cells. Same principle applies to any NAND flash or memory based device. No mechanical sensitivity though, so ideal for everyday use and carrying.
Cloud Storage Services
This is normally considered a reliable solution as data centers do have enterprise level data security and redundancy policies in place. They mostly use HDDs though and in data centers they tend to have a 1-3% failure rate that they replace every year. Pretty convenient solution it may be as a 3rd copy for the end user, there's a catch: you just rent the space and you don't have total control over your files. They may or may not be safe or exposed. Choose a company carefully. And then should you forget to renew your subscription and your files will be deleted.
These are becoming slowly obsolete among the average consumers as we start to use streaming services more and more, but for many reasons they are still very relevant for archiving purposes and considered the most reliable storage media to date. With at least 15 years of data retention on the better quality discs and 50-100 years on archival quality discs they're far superior in that regard to anything magnetic, hands down. Needless to say that you may want to steer clear from the cheap second or third grade discs, as those are not a reliable solution at all and many may fail right away during the burning process or their organic data layers degrade after a while, especially if exposed to UV light. Look for the "archival" label on well-known brands. There's also a special breed called M-disc, and they claim it can store data for nothing short of a millennium. Hence the name: Millennial-Disc or M-disc for short.
Furthermore because it's optical, it isn't sensitive to magnetic interference and can't be erased by strong magnetic fields.
It is currently the only medium that you can throw in a safe and leave it for a decade and be 99% sure when you come back the data will be still there, if it hasn't been physically destroyed of course.
And for the optical drives that can read them, we have tons upon tons of those, so surely we will have some around for a long while.
After all we still can play VHS tapes in 2021, right? :)
Even if this means we would need to visit a specialist to copy over our grandparents' wedding videos to something more current in technology, it's still relatively easy to access for anyone. There's no reason to think we wouldn't be able to read optical discs in a few decades.
Long story short, if you'd like to keep your files safe, then follow the 3-2-1 backup strategy and then maintain your backups from time to time. Like once a year maybe you just read the files back and if one's not completely right, you still should be able to make a new copy of the other two.
To help identify such a data decay I also provide freeware tools with your valuable images on the storage drive you order from me. With that you can easily and quickly do an error checking or even recovering the damaged files right away onto a new medium. :)
You may also want to "refresh" the data on anything magnetic or electric even if there're no errors in the files - basically just rewrite the data on it. And for the optical discs, you may just want to keep them in a cool, dry, and dark place. This actually applies to all kind. And if you're paranoid, then get a few copies on M-disks and scatter them in the world - or your family realistically, given that your relatives don't live next door.
But in any way don't leave your wedding images on that very USB drive you get from your photographer. You pay a premium on the fancy packaging and the content (this should be priceless anyway :), not the actual device. The device is probably just some cheap unbranded stuff bought in bulk. Make at least a couple copies of that just to be on the safe side.