6 ms·

The tricky bit, especially for the small operater is keeping a working drive as long as you want to keep the storage.

by somat 15d ago

cyberax 15d ago
Yeah, the back-compat story for LTOs is not great. They are going to try and improve it starting with LTO-10. It was partially on purpose for the earlier LTO generations. The capacity/speed ratio was not too high, so you could just keep upgrading your library in the background every decade. It outweighed the complexity of designing backwards-compatible hardware. But it's becoming less practical now. LTO-4 is 1.6Tb with 160Mb read speed, so each tape takes just about 3 hours to read. LTO-10 is 40Tb with 400Mb read speed, resulting in more than 24 hours of time to read one tape. Drive availability is an interesting question in itself. Laser drivers are pretty complicated beasts themselves that require highly precise mechanics. Tape drives are much simpler, because the areal information density is about 3 orders of magnitude smaller than on optical media. The mechanical stuff that loads and unloads the tape and keeps it in tension is crazy, but it's all just regular "macroscopic" parts that can be custom-manufactured if needed.
- traceroute66 15d ago
  > 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=95783049 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-Technical-Paper-August-2022.pdf https://www.lto.org/wp-content/uploads/2022/08/LTO-UBER-Tech...
  - cyberax 15d ago
    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.

The tricky bit, especially for the small operater is keeping a working drive as long as you want to keep the storage.

by somat 15d ago

The tricky bit, especially for the small operater is keeping a working drive as long as you want to keep the storage.

Yeah, the back-compat story for LTOs is not great. They are going to try and improve it starting with LTO-10. It was partially on purpose for the earlier LTO generations. The capacity/speed ratio was not too high, so you could just keep upgrading your library in the background every decade. It outweighed the complexity of designing backwards-compatible hardware. But it's becoming less practical now. LTO-4 is 1.6Tb with 160Mb read speed, so each tape takes just about 3 hours to read. LTO-10 is 40Tb with 400Mb read speed, resulting in more than 24 hours of time to read one tape. Drive availability is an interesting question in itself. Laser drivers are pretty complicated beasts themselves that require highly precise mechanics. Tape drives are much simpler, because the areal information density is about 3 orders of magnitude smaller than on optical media. The mechanical stuff that loads and unloads the tape and keeps it in tension is crazy, but it's all just regular "macroscopic" parts that can be custom-manufactured if needed.

traceroute66 15d ago
> 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=95783049 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-Technical-Paper-August-2022.pdf https://www.lto.org/wp-content/uploads/2022/08/LTO-UBER-Tech...
- cyberax 15d ago
  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.