I have a 72-core server running CentOS 8, kernel 4.18.0-240, with FIO 3.27. I have 12 NVMe drives, each with 12 partitions, and am trying to run multiple jobs for each partition, with numjobs=16 and iodepth=32. I get a too many open files error from FIO. Which is fine, that's a lot of threads. If I change numjobs to 8, same error, if I change it to 4, FIO runs. Is there a hard or dynamic limit in FIO, and if so, what is it, or how is it calculated? Thanks! [global] ioengine=libaio direct=1 randrepeat=0 thread=1 time_based=1 ramp_time=300 runtime=900 group_reporting=1 norandommap iodepth=32 numjobs=4 bs=4k rw=randread [job-2-1] filename=/dev/nvme2n1p1 [job-2-2] filename=/dev/nvme2n1p2 [job-2-3] filename=/dev/nvme2n1p3 [job-2-4] filename=/dev/nvme2n1p4 [job-2-5] filename=/dev/nvme2n1p5 [job-2-6] filename=/dev/nvme2n1p6 (goes on like that for 12 drives * 12 partitions per drive)
