mmap for mmap'ed io, splice for using splice/vmsplice,
or sgio for direct SG_IO io. The latter only works on
Linux on SCSI (or SCSI-like devices, such as
- usb-storage or sata/libata driven) devices.
+ usb-storage or sata/libata driven) devices. Fio also
+ has a null io engine, which is mainly used for testing
+ fio itself.
iodepth=x For async io, allow 'x' ios in flight
overwrite=x If 'x', layout a write file first.
nrfiles=x Spread io load over 'x' number of files per job,