.. option:: --readonly
- Turn on safety read-only checks, preventing writes. The ``--readonly``
- option is an extra safety guard to prevent users from accidentally starting
- a write workload when that is not desired. Fio will only write if
- `rw=write/randwrite/rw/randrw` is given. This extra safety net can be used
- as an extra precaution as ``--readonly`` will also enable a write check in
- the I/O engine core to prevent writes due to unknown user space bug(s).
+ Turn on safety read-only checks, preventing writes and trims. The
+ ``--readonly`` option is an extra safety guard to prevent users from
+ accidentally starting a write or trim workload when that is not desired.
+ Fio will only modify the device under test if
+ `rw=write/randwrite/rw/randrw/trim/randtrim/trimwrite` is given. This
+ safety net can be used as an extra precaution.
.. option:: --eta=when
If you want a workload that has 50% 2k reads and 50% 4k reads, while
having 90% 4k writes and 10% 8k writes, you would specify::
- bssplit=2k/50:4k/50,4k/90,8k/10
+ bssplit=2k/50:4k/50,4k/90:8k/10
Fio supports defining up to 64 different weights for each data
direction.
With writefua option set to 1, write operations include
the force unit access (fua) flag. Default is 0.
+.. option:: sg_write_mode=str : [sg]
+ Specify the type of write commands to issue. This option can take three values:
+
+ **write**
+ This is the default where write opcodes are issued as usual.
+ **verify**
+ Issue WRITE AND VERIFY commands. The BYTCHK bit is set to 0. This
+ directs the device to carry out a medium verification with no data
+ comparison. The writefua option is ignored with this selection.
+ **same**
+ Issue WRITE SAME commands. This transfers a single block to the device
+ and writes this same block of data to a contiguous sequence of LBAs
+ beginning at the specified offset. fio's block size parameter specifies
+ the amount of data written with each command. However, the amount of data
+ actually transferred to the device is equal to the device's block
+ (sector) size. For a device with 512 byte sectors, blocksize=8k will
+ write 16 sectors with each command. fio will still generate 8k of data
+ for each command but only the first 512 bytes will be used and
+ transferred to the device. The writefua option is ignored with this
+ selection.
I/O depth
~~~~~~~~~
Scale sector offsets down by this factor when replaying traces.
+.. option:: replay_skip=str
+
+ Sometimes it's useful to skip certain IO types in a replay trace.
+ This could be, for instance, eliminating the writes in the trace.
+ Or not replaying the trims/discards, if you are redirecting to
+ a device that doesn't support them. This option takes a comma
+ separated list of read, write, trim, sync.
+
Threads, processes and job synchronization
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~