I've got a WD 14TB arriving this week and I've like to determine if it's proper spinning rust or SMR.

There's a very good answer at How to determine whether hard drive uses SMR which discusses this, but it's now over 4 years old, and I wondered if the art might have evolved a bit since it was written.

I'm considering a plan of attack involving:

  1. Use libzbc and/or sg3_utils to see if it indicates that it's SMR
  2. See if it supports TRIM
  3. Determine (using ATTO, or something similar) the blocksize that gives the highest throughput for random writes.
  4. Mikko's answer suggests using fio --name TEST --eta-newline=5s --filename=fio-tempfile.dat --rw=randwrite --size=500g --io_size=1500g --blocksize=10m --ioengine=libaio --iodepth=1 --direct=1 --numjobs=1 --runtime=3600 --group_reporting but:
  5. https://youtu.be/8oF0vj5WBO0 recommends: directing io to /dev/sdx. In any case a file of at least a few TB seems "safer" than 1500GB in case the CMR cache algorithms are clever enough to use a lot of the surface as CMR cache to start with.
  6. This same source also recommends iodepth=4, but says it makes little difference. Not really sure what to use here.
  7. Blocksize as reported from the ATTO test (to fill the CMR cache as quickly as possible)

Any other recommendations?

  • What's the model number, and have you checked what WD claims for it? Aug 30, 2020 at 22:57
  • No idea. It's an external I'm going to shuck.
    – Ian
    Aug 31, 2020 at 14:23
  • 1
    For sure, but the lack of a reliable place to "look it up" drives me to want to test it.
    – Ian
    Sep 1, 2020 at 7:36
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    Ian asked over on the fio mailing list. The replies from Damien Le Moal look useful...
    – Anon
    Sep 25, 2020 at 12:45
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    As far as I know, manufacturers are still dishonest and do not disclose if any given drive actually uses SMR or not. Some models may have explicit declaration of being true PMR or CMR drives and if you don't see such declaration, you should assume that the drive uses SMR nowadays. May 22, 2023 at 17:45


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