/proc/diskstats

https://www.kernel.org/doc/Documentation/ABI/testing/procfs-diskstats

What:        /proc/diskstats
Date:        February 2008
Contact:    Jerome Marchand <jmarchan@redhat.com>
Description:
        The /proc/diskstats file displays the I/O statistics
        of block devices. Each line contains the following 14
        fields:

         1 - major number
         2 - minor mumber
         3 - device name
         4 - reads completed successfully
         5 - reads merged
         6 - sectors read
         7 - time spent reading (ms)
         8 - writes completed
         9 - writes merged
        10 - sectors written
        11 - time spent writing (ms)
        12 - I/Os currently in progress
        13 - time spent doing I/Os (ms)
        14 - weighted time spent doing I/Os (ms)

        Kernel 4.18+ appends four more fields for discard
        tracking putting the total at 18:

        15 - discards completed successfully
        16 - discards merged
        17 - sectors discarded
        18 - time spent discarding

        Kernel 5.5+ appends two more fields for flush requests:

        19 - flush requests completed successfully
        20 - time spent flushing

        For more details refer to Documentation/admin-guide/iostats.rst
Click to copy

# for coreos
cat /proc/diskstats | awk 'BEGIN {printf("%s %s %4s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s\n" ,"major", "minor", "device", "reads/comp", "reads/merged", "sectors read", "spent(ms)", "writes/comp", "writes/merged", "sectors written", "spent(ms)", "I/Os", "spent(ms)", "weighted(ms)", "discards/comp", 
"discards/merged", "sectors discarded", "spent")}
{printf("%s %s %4s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s %10s\n", $1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18)}'Click to copy