Sadly, if you look at the mean-uncorrectable error rate you will notice that for a 2.5TB drive, the chance of getting an error when reading it all the way through is 100%. Or, basically you can't use 'mirror' RAID to protect your data because you can't reliably read the entire drive.

New and more interesting error correcting bits are going to be needed here. I could imagine a device with 60TB of raw capacity providing 20TB of data you could read reliably though.

A couple of thoughts.

WD lists their 2.5TB drive as having "Non-recoverable read errors per bits read" as "<1 in 10^14" and the drive has about 2 x 10^13 bits, so while the chance of an error in one whole disk read is non-trivial, it's not 100%.

Mirroring will still work fine as long as the error is detected. The chance of read errors in the exact same sector of two disks should still be small. Silent errors were always a problem for mirroring.

At what point do we as consumers start considering drives to be defective? Is the underlying ECC suffering because of the need to hit greater storage numbers?

The day came for me back in about 1998. Ever since then, the smallest drive money could buy has been much, much larger than the sum total of all the data I owned.

I may be conservative, though. I mean, I also still instinctively gauge program size by how many floppies it would take up . . .

I agree. Storage needs are increasing, but not faster than the technology. Some types of data just stay the same size.

Depends on what you do. If you do video, HDDs are actually behind the tech. Every time they double the resolution (DVD -> 1080p -> 4k -> 8k), you need 4 times more space. That's not even considering lossless formats, which need even more space.

Same with photography. Each raw photo from my 5D II is 25MB. The megapixel race isn't over.

Now you've got me curious. Are you saying lossless video formats require more than four times the space to store four times the pixels? How can that possibly be?

I believe OP was meaning that the storage requirements for compressed video are already increasing at a huge rate, and it's exacerbated if you are working with uncompressed video

By the end of this decade we will have extremely high resolution displays pushing 10k x 6k most likely (consumer, given the ipad3 just came out and it took us 6 years for 1080p to get mainstream and ultra high resolution is in labs), and encoding video for that resolution will be on the order of potentially hundreds of gigabytes per hour, even with how lossy container formats like vorbis allow a logarithmic size growth relative to resolution.

I don't see the rate at which we use space slowing down any time soon, but we have physical magnetic platter limits to worry about going forward.

We will always have room for more space!

the amount of storage you use and need grows over time, so this may be a hard dream to achieve. If I look at how much storage I require now compared to just 10 years ago, it is more than quadrupled. I expect that trend to continue.

For sure. However, lately, I've been seeing the storage growth rate increase faster than my personal use growth rate. Maybe it's just me.

Hard drive capacities have increased far more than fourfold in that 10 years, though.

which is why I have 1.5 TB left on my main storage.