f3probe with USB reset results in an incorrect result

[hedayat]

Run f3 7.0 with default settings:

f3probe --destructive --time-ops /dev/sdb
F3 probe 7.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.

WARNING: Probing normally takes from a few seconds to 15 minutes, but
         it can take longer. Please be patient.

        Bad news: The device `/dev/sdb' is a counterfeit of type limbo

You can "fix" this device using the following command:
f3fix --last-sec=33554431 /dev/sdb

Device geometry:
                 *Usable* size: 16.00 GB (33554432 blocks)
                Announced size: 30.00 GB (62914560 blocks)
                        Module: 32.00 GB (2^35 Bytes)
        Approximate cache size: 0.00 Byte (0 blocks), need-reset=yes
           Physical block size: 512.00 Byte (2^9 Bytes)

Probe time: 6'24"
 Operation: total time / count = avg time
      Read: 692.8ms / 4199 = 164us
     Write: 5'55" / 2148 = 165.5ms
     Reset: 28.60s / 24 = 1.19s

Run with -s 2:

[root@localhost hedayat]# f3probe --destructive --time-ops /dev/sdb -s 2
F3 probe 7.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.

WARNING: Probing normally takes from a few seconds to 15 minutes, but
         it can take longer. Please be patient.

Good news: The device `/dev/sdb' is the real thing

Device geometry:
                 *Usable* size: 30.00 GB (62914560 blocks)
                Announced size: 30.00 GB (62914560 blocks)
                        Module: 32.00 GB (2^35 Bytes)
        Approximate cache size: 0.00 Byte (0 blocks), need-reset=no
           Physical block size: 512.00 Byte (2^9 Bytes)

Probe time: 15'06"
 Operation: total time / count = avg time
      Read: 694.7ms / 4815 = 144us
     Write: 15'04" / 4192321 = 215us
     Reset: 0us / 1 = 0us

Running a full f3write/f3read confirms that the device is really OK.

I know that -s 2 is now default in f3 7.1; but still the results might be interesting for you.

Thanks!

[AltraMayor]

Thank you for bringing this to my attention. I don't know how to use this information now, but it may help me to solve a problem down the line.