Le 13/04/2021 à 08:13, Nakajima Akira a écrit : > Hi. > > I'm using fio for the first time. Sorry for the basic question. > > On RHEL 8.3 > # fio -filename=/mnt/testfile -direct=1 -ioengine=libaio -rw=write > -bs=1m -size=5G -numjobs=1 -runtime=60 -group_reporting -name=test > IOPS=366, BW=366MiB/s > > But when -numjobs=10 > IOPS=3358, BW=3358MiB/s > This is 5 times faster than the physical speed of the HDD I am using > (600MB/s). > Similar results are obtained with Sequential write. > Random read/write is fine.(Results are within 600MB/s) > > https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ffio.readthedocs.io%2Fen%2Flatest%2Ffio_man.html%23target-file-device&data=04%7C01%7Ce.velu%40criteo.com%7Cdd41a8193e6048f16cc408d8fe441b34%7C2a35d8fd574d48e3927c8c398e225a01%7C1%7C1%7C637538915767435166%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000&sdata=7jscmG7bnj%2BSBE%2BgbwVWNbz%2BTQhhckXAP%2Bl7xa%2F%2FuHo%3D&reserved=0 > > I refer above and use -directory=/mnt/testdir instead of -filename > gave good results. > > Am I using the -filename option incorrectly? Hey, You are performing your benchmark against the filesystem which uses the memory as cache. So here, you are benchmarking your memory (which is correlated by the 3GB/sec speed). You can use direct=1 to avoid using the buffer as per https://fio.readthedocs.io/en/latest/fio_doc.html#i-o-type If you want to test the disk itself, not the filesystem, it would be better to use the block device directly (/dev/sd<x>) and remove this unecessary layer. Erwan,
