https://docs.fluentbit.io/manual/pipeline/inputs/disk-io-metrics

[INPUT]
    Name cpu
    Tag cpu
    interval_sec 1 # 폴링 간격 (초)
    interval_nsec 0 # 폴링 간격 (나노초)
    dev_name sda # 디스크 이름 (기본값: 모든 디스크)

[OUTPUT]
    Name stdout
    Match cpu

로그는 다음과 같다

$ fluent-bit -i disk -o stdout
Fluent Bit v1.x.x
* Copyright (C) 2019-2020 The Fluent Bit Authors
* Copyright (C) 2015-2018 Treasure Data
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* <https://fluentbit.io>

[2017/01/28 16:58:16] [ info] [engine] started
[0] disk.0: [1485590297, {"read_size"=>0, "write_size"=>0}]
[1] disk.0: [1485590298, {"read_size"=>0, "write_size"=>0}]
[2] disk.0: [1485590299, {"read_size"=>0, "write_size"=>0}]
[3] disk.0: [1485590300, {"read_size"=>0, "write_size"=>11997184}]