The spin-up/spin-down behavior is normal for LTO drives, because they need to make multiple passes on the tape to fill it up and the drive needs to slow down and stop momentarily at the ends of the tape.
Something that should be considered is that it may take many dozens to hundreds of passes to fill up a tape, but tape life cycle is measured in end-to-end passes so filling up a tape could use up as many as ~200 cycles out of the 10,000-20,000 cycle limit most tapes have.
Good tip from @twin_savage: even an LTO tape & drive working perfectly will have brief pauses every few minutes as the tape switches directions for another pass. How often are you seeing (or hearing) it?
LTO-4 has a maximum speed of 120Mbps. If you’re seeing around 234Mbps most of the time, your “bigfile” is something that compresses quite well like a text file, disk image, or SQL dump. If it can be compressed more than 2:1, you’ll hit compression speed limits on your LTO drive throughput, and the tape will spin down (possibly quite a lot) because of it. Much better to compress your bigfile (or any other data) in software with pigz/xz/zstd/etc. first, before sending it to tape to avoid this.
Is the buffer staying in the double-digit “% full” range the whole time?
As for other a few suggestions, see my prior post:
Probably needs compression to deal with unused empty disk space before sending to tape. If your CPU is fast enough, you can do it in a pipeline on-the-fly like:
