Can you qualify what "2 different forms of media" means? I'm assuming one physical, one cloud. Do you consider two separate external HDD's with the data on it to fail that test because they are the same form?

When my music collection was smaller, I had everything backed up onto an external as well as had them all physically burned onto like 50 DVDs. Since my collection has grown beyond a terabyte, however, I haven't had the time or energy to keep that up. Now it's just an external, a travel external, a redundant external, and a cloud backup.

A few examples I can pull off the top of my head - DVD, Disk (HDD), Disk (SSD), Disk (Flash.. maybe?), Tape, Cloud

So Disk (HDD) and Cloud is fine. Two HDDs (spinny platter style) would indeed fail the test. If you want to argue it you could probably get away with different manufacturers or different batches but I'd prefer my backups to play nicely with the rules rather than try to avoid them! Far-fetched as it is but lets say for example you have a power surge that takes out your external disk (is that even possible?). Chances are high whatever did that would also do that to your other disk. Or maybe a wall caves in and decimates your PC (or you just sweep the desk somehow and knock everything off it. Maybe the desk has collapsed) - The spinny disks may be destroyed if they are both hit hard enough. Mixing an HDD and SSD, the SSD would probably be more hardy against shock damage.

From another comment I made in this thread somewhere "I consider "cloud" as its own media type to avoid the pedantics of me storing files on a spinning disk and the cloud provider does too. Chances are they have server grade disks and their own backups [so it's different to just a raw disk]"

Edit: I use too many brackets here. I am going to attend my next available parenthesis anonymous support group.

One nice thing about the "2 different forms of media" rule is that it would protect you against bad batches of hard drives.

Sometimes, when people buy multiple drives at once for servers, they wind up with drives from the same batch. If the drives are subtly defective, and if they're always run under identical conditions (such as in a RAID array), then I've seen multiple drives fail within days of each other.

Running two identical disks in a RAID, or where the same desk could cave in and sweep them off, seems like it should be covered by "1 offsite" rather than requiring two different types of media.

Adding my own[0] rule here:

Disks exists in two states: failed and failing.

[0]: please feel free to let me know if you know any previous references to this rule.

Does three copies include the original?

I believe it does traditionally, yes. Your data plus two backup copies. Personally I'd say no though, just for the sake of having more backups (3 2 1 is minimum, not strict!).

Partially unrelated I consider "cloud" as its own media type to avoid the pedantics of me storing files on a spinning disk and the cloud provider does too. Chances are they have server grade disks and their own backups. On that note, their backups are not my backups. Their backups are never my backups.

If they save my butt one day, awesome. But that day was already terrible if I'd managed to lose all of my backups.

> But that day was already terrible if I'd managed to lose all of my backups.

I have two off-site backups located ~150 miles from each other. If I (we) lose everything, chances are that there are more important things to worry about, like what's for dinner.