randread Random reads
rw,readwrite Sequential mixed reads and writes
randrw Random mixed reads and writes
+ trimwrite Mixed trims and writes. Blocks will be
+ trimmed first, then written to.
For the mixed io types, the default is to split them 50/50.
For certain types of io the result may still be skewed a bit,
If set, fio will use POSIX_FADV_SEQUENTIAL for sequential
IO and POSIX_FADV_RANDOM for random IO.
+fadvise_stream=int Notify the kernel what write stream ID to place these
+ writes under. Only supported on Linux. Note, this option
+ may change going forward.
+
size=int The total size of file io for this job. Fio will run until
this many bytes has been transferred, unless runtime is
limited by other options (such as 'runtime', for instance,
zero_buffers If this option is given, fio will init the IO buffers to
all zeroes. The default is to fill them with random data.
- The resulting IO buffers will not be completely zeroed,
- unless scramble_buffers is also turned off.
refill_buffers If this option is given, fio will refill the IO buffers
on every submit. The default is to only fill it at init
necessary environment variables to work with
hdfs/libhdfs properly.
+ mtd Read, write and erase an MTD character device
+ (e.g., /dev/mtd0). Discards are treated as
+ erases. Depending on the underlying device
+ type, the I/O may have to go in a certain
+ pattern, e.g., on NAND, writing sequentially
+ to erase blocks and discarding before
+ overwriting. The writetrim mode works well
+ for this constraint.
+
external Prefix to specify loading an external
IO engine object file. Append the engine
filename, eg ioengine=external:/tmp/foo.o
command line parameter. The files will be stored with a
.fz suffix.
+block_error_percentiles=bool If set, record errors in trim block-sized
+ units from writes and trims and output a histogram of
+ how many trims it took to get to errors, and what kind
+ of error was encountered.
+
lockmem=int Pin down the specified amount of memory with mlock(2). Can
potentially be used instead of removing memory or booting
with less memory to simulate a smaller amount of memory.
completion latencies.
percentile_list=float_list Overwrite the default list of percentiles
- for completion latencies. Each number is a floating
- number in the range (0,100], and the maximum length of
- the list is 20. Use ':' to separate the numbers, and
- list the numbers in ascending order. For example,
- --percentile_list=99.5:99.9 will cause fio to report
- the values of completion latency below which 99.5% and
- 99.9% of the observed latencies fell, respectively.
+ for completion latencies and the block error histogram.
+ Each number is a floating number in the range (0,100],
+ and the maximum length of the list is 20. Use ':'
+ to separate the numbers, and list the numbers in ascending
+ order. For example, --percentile_list=99.5:99.9 will cause
+ fio to report the values of completion latency below which
+ 99.5% and 99.9% of the observed latencies fell, respectively.
clocksource=str Use the given clocksource as the base of timing. The
supported options are:
1 : allocate space immidietly inside defragment event,
and free right after event
+[mtd] skip_bad=bool Skip operations against known bad blocks.
6.0 Interpreting the output