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traceroute66today at 6:14 PM1 replyview on HN

> Tape drives are much simpler

Maybe back in the 90's :)

LTO-9 increased track density, increased the total number of tracks by reducing their width and increased linear density.

The "how" certainly does not sound "much simpler" to me ?[1]

    The new, narrower track width was achieved through a combination of improvements in tracking
    performance, new, narrower tunneling magnetoresistive (TMR) readers within the head assembly
    (now <1000nm in width) and optimized writers. The narrower tracks also necessitated
    improvements to the media magnetic layer. Magnetic particles are Barium Ferrite (BaFe) as in LTO-8, but with
    improved characteristics to support the higher linear densities.

    Changes were also made to the tape substrate, with the thickness reduced by 7% from 5.6µm to
    5.2 µm. This in turn enables more tape to fit on the reel – tape length per cartridge has
    increased from 960m to 1035m. The new substrate also features optimized stability
    characteristics to mitigate tape dimensional variations that occur due to fluctuations in
    environmental conditions.
In addition the LTO Program's own technical paper describes how LTO-9 manages dimensional changes in the new substrate with a one-time-per-tape calibration algorithm to control 32-channel recording via closed-loop servo algorithms, plus a longer-block Reed-Solomon C2 code — together getting LTO-9's uncorrectable bit error rate to 10⁻²⁰, a 10× improvement over LTO-8[2]

[1] https://at.ingrammicro.eu/api/cfs/Icecat/PDF.ashx?l=en&s=957... [2] https://www.lto.org/wp-content/uploads/2022/08/LTO-UBER-Tech...


Replies

cyberaxtoday at 8:10 PM

Sure, but that's an order of magnitude better than optical drives. Blu-Ray optical media use feature sizes on the order of 100nm (0.1um) and the read head needs to be able to move in two dimensions to keep it in focus.

I repaired a couple of LTO drives, and they are pretty approachable once you disassemble the Ruby Goldberg tape management devices.

A lot of LTO complexity also matters for _writing_, not reading. If you're an archivist trying to restore a tape, you don't need to worry about optimal tensioning, calibration, etc. You can also read the tape at a fraction of the normal speed so that your control loops can be much looser.