How to check the erase block size of a USB flash under Linux?

Someone said /proc/mtd might be helpful, while for my Centos7 server, there isn't such file.

Thanks in advance.

Updated on Jan 28 2016:

Below is my output of flashbench, would anyone confirm that my erase block size if 4M? (Actually, my sdb is a Kingston DTSE9G2 128G USB flash.)

# ./flashbench -a /dev/sdb
sched_setscheduler: Operation not permitted
align 34359738368   pre 461µs   on 584µs    post 443µs  diff 132µs
align 17179869184   pre 468µs   on 598µs    post 463µs  diff 133µs
align 8589934592    pre 473µs   on 598µs    post 467µs  diff 128µs
align 4294967296    pre 476µs   on 602µs    post 470µs  diff 129µs
align 2147483648    pre 473µs   on 599µs    post 462µs  diff 131µs
align 1073741824    pre 463µs   on 601µs    post 465µs  diff 137µs
align 536870912 pre 463µs   on 595µs    post 469µs  diff 129µs
align 268435456 pre 463µs   on 581µs    post 452µs  diff 124µs
align 134217728 pre 467µs   on 585µs    post 454µs  diff 125µs
align 67108864  pre 452µs   on 580µs    post 458µs  diff 125µs
align 33554432  pre 471µs   on 604µs    post 463µs  diff 137µs
align 16777216  pre 457µs   on 588µs    post 473µs  diff 123µs
align 8388608   pre 459µs   on 603µs    post 471µs  diff 138µs
align 4194304   pre 465µs   on 569µs    post 465µs  diff 104µs
align 2097152   pre 467µs   on 584µs    post 473µs  diff 114µs
align 1048576   pre 450µs   on 579µs    post 474µs  diff 118µs
align 524288    pre 472µs   on 581µs    post 454µs  diff 117µs
align 262144    pre 465µs   on 581µs    post 462µs  diff 117µs
align 131072    pre 461µs   on 583µs    post 471µs  diff 117µs
align 65536 pre 453µs   on 573µs    post 465µs  diff 114µs
align 32768 pre 453µs   on 561µs    post 454µs  diff 107µs
  • the correct command to use is flashbench -a [device] --blocksize=1024
    – Hydranix
    Apr 19, 2016 at 2:55

1 Answer 1


You could have a look at the flashbench tool. I don't think that this kind of property is exported by the device reliably.

  • Thanks a lot. I believe flashbench would be helpful, while it doesn't provide direct answer but need I guess. Would you check my update on Jan 28 and provide a confirmation? Jan 28, 2016 at 7:08

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