Ok, I know I have to preface this with I work for IBM. So know that all disclaimers are out lets start. If they do come out with 2.5TB HDDs, and you put that drive into a RAID array, say a drive fails. Sure, you're protected against this with RAID protection right? Ok, so you have a hotspare drive of the same size, do you know how long it takes to rebuild a drive of say 500GB in a RAID 5 array? Just to simplify it, it's so long, your starting to see disk manufacturers implement dual parity array's. This is directly because the drive rebuild times are getting so large you run a much higher risk in having a second drive in the array go out before the rebuild is complete. Another bad thing about extremely dense drives, performance. Can you imagine the random seek time on a drive of this capacity? What's the top spindle speed in the market today, 15krpm. And mind you on the 500GB SATA 2 drives you're still only getting 7.2krpm. This will kill performance until we find a much quicker way to access the data on the HDD's. So, what do you use these large capacity drives for? Primarily large sequential I/O's. What does (LTO) tape perform best at, large sequential I/O's. Also, what is the life span of a disk drive? I'll tell you, it's much less than a tape cartridge. So all these federal compliance regulations that state a company must keep data for x ammount of time (3 yrs, 7 yrs, 30 yrs...) disk just doesn't make sense. From IBM's side, sure, I would love for you to use disk for everything, it's more expensive, you have to buy more of it, and 3-5 years from now, you'll have to replace it. LTO has a standard that n-1 generation carts must be able to be read and written by the current version drives, and n-2 must be able to be read by the current drives.

Now will your small shops be interested in this, no, but if you're a large company that has data retention policies, then tape just makes good sense.

Again, I'm an IBM employee so you can take this as you will, but I just want you to know tape has been and will be around for a long time.