> The read-write head has 32 read-write elements. Each element contains a write component sandwiched between two read components – one for reading, the other for read-after-write checking. The overall read-write head reads or writes 32 adjacent tracks at once. This group of 32 adjacent tracks running the length of the tape is called a wrap. The write tracks are partially overlapped, leaving a clearly readable read track, narrower and in the middle of its write track. This track overlapping is called shingling after shingled roof tiles, and is a way of cramming more write tracks into a data band to increase the tape’s capacity.

* https://www.blocksandfiles.com/tape/2025/07/29/why-lto-10-fe...

> The tape drives use a strong error correction algorithm that makes data recovery possible when lost data is within one track. Also, the head assembly includes separate read heads positioned just "behind" each write head, to verify the data just written without making a separate verification pass. This allows the drive to write a second copy of any data that fails the verify without the help of the host system.

* https://en.wikipedia.org/wiki/Linear_Tape-Open#Logical_struc...

I think the issue arises if the tape is out of alignment - ie. too high or too low. Then it writes in the wrong spot, reads in the wrong spot, so you think all is good...

But when you try to read it back with a different, correctly aligned machine, it is unreadable.