The best backup strategy, outlined and explained.
Why back up files?
it's been said that drive failure is not a case of 'if', but when". Sooner or later, even the most reliable drive, whether digital or spinning rust, will fail. to this end, ever since data storage has been a thing, so has some form of backup.
What is "3-2-1"?
it's the one IT experts recommend. Simply put, it is three copies of data, on two differing media, one of which is held offsite. So in the case of a phone or personal computer, you have one copy on the device. A sensible soul would therefore keep two additional copies, one of which is not physically with the other two. Why is here an "offsite" option? Imagine the worst case scenario. Your laptop is backed up to an external drive, which you keep in he same house. You have a burglary, or a fire. If both devices are lost, it results in a catastrophic loss of all that data. If there's a third device not on the same premises, that backup means you can recover. That option could be a separate drive that is kept at another location (with a friend or relative), or it could be some form of cloud storage like Google Drive, Dropbox or an Amazon s3 bucket.
What do i need to back up?
Anything you cannot afford to lose, or that is otherwise irreplaceable. this might include business or personal documents, anything you have created (a journal, writings, personal photos). It does not includes anything you can download or recreate (like downloaded music or other media, or things you've ripped from CD or DVD and for which you have the physical media secured). In my case, it's photos and videos from my phone, various writings and scanned copies of important documents.
RAID is not a backup
'But my data is on a RAID array!", I hear some cry. RAID sands for Redundant Array of Inexpensive Disks and is a method of providing better integrity of data by sharing it across two or more drives. There are many standards, ways of achieving this, but there's a caveat: drives can still fail catastrophically at any time, and this is not a backup.
Some suggestions
At the minimum, I suggest two removable drives you can connect via USB, or a Network Attached Storage (NAS) device and anotherdrive for backup. The third copy, once made, can be removed to a separate location, be it a friend's premises, a locker at work (or a waterproof cache in the woods for all i care). My current setup is three USB drives, which i back up once or twice a week using a little script. One drive I then swap weekly with a friend who uses the same strategy. Then i continue with the third drive, which replaces the original offsite backup. Rinse, repeat, this way, each of us safeguards a backup of the others' data and everyone is happy. Many of my photos (and those from Christine's old phone) also live on Dropbox for fast retrieval.
My future plans do include a homebuilt NAS using a second-hand desktop machine rigged with extra storage, and some NAS software running in a virtual machine. If that seems vague it's because I'm in the early planning stage, but i have the concept.
For one thing, it's out of my control. Basically, the cloud is just someone else's computer. Dropbox might change their terms and conditions, Google might decide that something is suspicious and decline to keep it, or delete it. Both these things have happened to others and i'm not about to test it.
$ xclip -o | wc -w
607