On my 3rd ship (late 80's & early 90's thru dessert storm) we got a rather expensive tape certifying machine. Over half of brand new tapes would fail. Cheap garbage tapes.
I don't have any direct knowledge, but I suspect tapes are no longer used. There are so many much better, cheaper and vastly more compact methods to store vast amounts of data. Heck a thumb drive will hold more data, and is vastly faster and more reliable. I have one plugged into a port in my router at home. It holds all of our pics, all of our movies, and tons of other data. And yes that is backed up in several other places.
On my last ship (the Kitty Hawk) before I got out of the navy our data system was converted to much more modern gear, PCs replaced terminals, minis replace the old servers. We still had tapes though, legacy support. But they were small units. The worked much better. Was not a lot of parts that I could replace or fix. No vacuum systems that were maintenance hogs.
Ken