LTO 5 will be readable as long as there are LTO 7 drives available in the market. For example, there are still LTO 3 drives available – LTO 1 tapes can still be read today – that’s 13 years after introduction.
However, anytime you hear “migration” question – I work to bring up two fundamental points. First – “migration” is a result of proprietary tape software stacks. That is, cost and complexity in “migrating” in tape is not a tape technology issue, it’s a result of the software used with tape. For example, disk are “migrated” every 3 years on average. We don’t think of it as “migration” because it’s either a failure replacement or a forklift upgrade of the system. In either case, the data is moved or recreated easily. It’s a copy from where ever the data was to it’s new home. In tape, because traditionally proprietary software was used to move data, when a customer wanted to upgrade – they had to get new hardware and get an upgrade to their software application (which usually was a newer version, with different support and features) and perform the “migration”.
With LTFS all that changes. In an LTFS based tape solution, it’s no harder to copy from LTO 5 to LTO 7 than it is to roll up a new disk system. In fact, it’s arguably easier as both LTO 5 and LTO 7 can be in the same library and running side by side for as long as you desire so the upgrade can be managed seamlessly over as long as period as you desire.
So – the key is – with LTFS, we no longer “migrate”, we “upgrade” – no different (maybe better) than disk upgrades
Second – the question to think about is: “If you could keep the same storage device (ie. in this case a LTO 5 cartridge) for 25 years – would you really want to?” Around 25 years ago, the dominate removable storage was a 1.4Mb floppy. If one could use this today, would they really want it compared to the speed, capacity, performance of today’s technology? In 25 years, assuming 12 generations – we will be able to put 4000 LTO 5s on a single LTO 17. We can put 15 LTO 1s on a LTO 5 (we rounded the 1.6TB to 1.5TB, so instead of 2^4=16 we ended up with a 15x)
So if you can move the discussion away from “migration” to a discussion on how they want to manage their data and the alternatives – tape compares well. If they want to keep it in one removable storage device – we’ve already demonstrated 12 year life, the media can last 30 and if there is a market demand for LTO 1 capable tape devices, LTO is an open format and the market will create the devices. If they want to upgrade their storage technology to take advantages of the latest capabilities, lower costs, etc. – then tape with LTFS upgrades easier than disk.