.. option:: --parse-only
- Parse options only, don\'t start any I/O.
+ Parse options only, don't start any I/O.
.. option:: --output=filename
``sequential`` is only useful for random I/O, where fio would normally
generate a new random offset for every I/O. If you append e.g. 8 to randread,
- you would get a new random offset for every 8 I/O's. The result would be a
- seek for only every 8 I/O's, instead of for every I/O. Use ``rw=randread:8``
+ you would get a new random offset for every 8 I/Os. The result would be a
+ seek for only every 8 I/Os, instead of for every I/O. Use ``rw=randread:8``
to specify that. As sequential I/O is already sequential, setting
``sequential`` for that would not result in any differences. ``identical``
behaves in a similar fashion, except it sends the same offset 8 number of
.. option:: log_offset=int
If this is set, the iolog options will include the byte offset for the I/O
- entry as well as the other data values.
+ entry as well as the other data values. Defaults to 0 meaning that
+ offsets are not present in logs. Also see `Log File Formats`_.
.. option:: log_compression=int
**ios**
Number of I/Os performed by all groups.
**merge**
- Number of merges I/O the I/O scheduler.
+ Number of merges performed by the I/O scheduler.
**ticks**
Number of ticks we kept the disk busy.
**in_queue**
change.
Split up, the format is as follows (comments in brackets denote when a
-field was introduced or whether its specific to some terse version):
+field was introduced or whether it's specific to some terse version):
::
Fio supports a variety of log file formats, for logging latencies, bandwidth,
and IOPS. The logs share a common format, which looks like this:
- *time* (`msec`), *value*, *data direction*, *offset*
+ *time* (`msec`), *value*, *data direction*, *block size* (`bytes`),
+ *offset* (`bytes`)
-Time for the log entry is always in milliseconds. The *value* logged depends
+*Time* for the log entry is always in milliseconds. The *value* logged depends
on the type of log, it will be one of the following:
**Latency log**
**2**
I/O is a TRIM
-The *offset* is the offset, in bytes, from the start of the file, for that
-particular I/O. The logging of the offset can be toggled with
-:option:`log_offset`.
+The entry's *block size* is always in bytes. The *offset* is the offset, in bytes,
+from the start of the file, for that particular I/O. The logging of the offset can be
+toggled with :option:`log_offset`.
Fio defaults to logging every individual I/O. When IOPS are logged for individual
-I/Os the value entry will always be 1. If windowed logging is enabled through
+I/Os the *value* entry will always be 1. If windowed logging is enabled through
:option:`log_avg_msec`, fio logs the average values over the specified period of time.
If windowed logging is enabled and :option:`log_max_value` is set, then fio logs
-maximum values in that window instead of averages. Since 'data direction' and
-'offset' are per-I/O values, they aren't applicable if windowed logging is enabled.
+maximum values in that window instead of averages. Since *data direction*, *block
+size* and *offset* are per-I/O values, if windowed logging is enabled they
+aren't applicable and will be 0.
Client/Server
-------------