It has been over a year since Oracle announced T10000C, and not many months later IBM announced TS-1140. Both have huge densities over LTO-5. (Uncompressed density of 5TB for T10000C and 4 TB for TS-1140.) LTO-5 is still at 1.5 TB, and LTO-6 is still unannounced as far as I know. My understanding based on official statementsis that LTO-6 will offer a storage capacity of up to 8.0 terabytes compressed, or 3.2 TB native.
Let's assume LTO-6 comes out at 3.2 TB, and let's assume this happens in 2013, as there have been no official announcements about LTO-6 so far in 2012. We can also assume that neither Oracle nor IBM will stand still. For many years, LTO density was greater than enterprise density. This is the first time both enterprise tape vendors have greater density than LTO.
So what does that mean for the LTO format? Before, LTO had a number of advantages over enterprise tape price, density and interoperability. Now, it has two advantages, and part of the price advantage was that since it had greater density it used few slots in the tape library. That part of the price equation has been lost. I know a number of our customers are currently moving to enterprise tape from LTO because of the density improvements and the savings in floor space because fewer library slots are needed.
What is best for you depends on many many factors including, library slots, tapes drives, media and floor space, but it might be time to consider doing a pricing exercise to compare the cost of enterprise tape with LTO. I have been waiting for a press release about LTO-6 for over six months. The longer it takes the more concerned I get.