Single-depth latency probe

Pure per-IO latency at iodepth=1; reports p99/p99.9/p99.99 tail latency

fio --name=latency --filename=/dev/<id> --rw=randread --bs=4k --iodepth=1 --numjobs=1 --runtime=30 --time_based --direct=1 --percentile_list=99:99.9:99.99
tool
fio5 commands
tags
fiodiskperformancetroubleshooting

More fio commands

  • Mixed 70/30 read-write
    fio --name=mixed --filename=/data/testfile --size=8G --rw=randrw --rwmixread=70 --bs=4k --iodepth=32 --numjobs=4 --runtime=120 --time_based --direct=1 --group_reporting

    Realistic mixed workload 70% read / 30% write; closer to OLTP than pure tests

  • 4k random read IOPS
    fio --name=randread --filename=/dev/<id> --rw=randread --bs=4k --iodepth=32 --numjobs=4 --runtime=60 --time_based --direct=1 --group_reporting

    4k random read IOPS test; note: --direct=1 bypasses page cache for true device numbers

  • 4k random write IOPS
    fio --name=randwrite --filename=/data/testfile --size=4G --rw=randwrite --bs=4k --iodepth=64 --numjobs=4 --runtime=60 --time_based --direct=1 --group_reporting

    4k random write IOPS on a file; note: destroys data if filename is a raw device

  • Sequential throughput
    fio --name=seqwrite --filename=/data/testfile --size=10G --rw=write --bs=1M --iodepth=16 --direct=1 --runtime=60 --time_based --group_reporting

    Sequential write throughput (MB/s) with large 1M blocks and direct I/O

all 5 fio commands