Adds verify_only option

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index eb2ed25403cb8dfe2ae96e8a93d5e99aa98c8b39..9830fa1ebd9510f693c3978c70c5c9121d7eabdd 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -384,6 +384,11 @@ unified_rw_reporting=bool  Fio normally reports statistics on a per
 randrepeat=bool        For random IO workloads, seed the generator in a predictable
                way so that results are repeatable across repetitions.
 
+randseed=int   Seed the random number generators based on this seed value, to
+               be able to control what sequence of output is being generated.
+               If not set, the random sequence depends on the randrepeat
+               setting.
+
 use_os_rand=bool Fio can either use the random generator supplied by the OS
                to generator random offsets, or it can use it's own internal
                generator (based on Tausworthe). Default is to use the
@@ -542,6 +547,11 @@ buffer_compress_chunk=int  See buffer_compress_percentage. This
                alternate random and zeroed data throughout the IO
                buffer.
 
+buffer_pattern=str     If set, fio will fill the io buffers with this pattern.
+               If not set, the contents of io buffers is defined by the other
+               options related to buffer contents. The setting can be any
+               pattern of bytes, and can be prefixed with 0x for hex values.
+
 nrfiles=int    Number of files to use for this job. Defaults to 1.
 
 openfiles=int  Number of files to keep open at the same time. Defaults to
@@ -695,6 +705,11 @@ direct=bool        If value is true, use non-buffered io. This is usually
                O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
                On Windows the synchronous ioengines don't support direct io.
 
+atomic=bool    If value is true, attempt to use atomic direct IO. Atomic
+               writes are guaranteed to be stable once acknowledged by
+               the operating system. Only Linux supports O_ATOMIC right
+               now.
+
 buffered=bool  If value is true, use buffered io. This is the opposite
                of the 'direct' option. Defaults to true.
 
@@ -876,6 +891,20 @@ rate_iops_min=int If fio doesn't meet this rate of IO, it will cause
                the job to exit. The same format as rate is used for read vs
                write separation.
 
+latency_target=int     If set, fio will attempt to find the max performance
+               point that the given workload will run at while maintaining a
+               latency below this target. The values is given in microseconds.
+               See latency_window and latency_percentile
+
+latency_window=int     Used with latency_target to specify the sample window
+               that the job is run at varying queue depths to test the
+               performance. The value is given in microseconds.
+
+latency_percentile=float       The percentage of IOs that must fall within the
+               criteria specified by latency_target and latency_window. If not
+               set, this defaults to 100.0, meaning that all IOs must be equal
+               or below to the value set by latency_target.
+
 max_latency=int        If set, fio will exit the job if it exceeds this maximum
                latency. It will exit with an ETIME error.
 
@@ -1039,6 +1068,13 @@ loops=int        Run the specified number of iterations of this job. Used
                to repeat the same workload a given number of times. Defaults
                to 1.
 
+verify_only    Do not perform specified workload---only verify data still
+               matches previous invocation of this workload. This option
+               allows one to check data multiple times at a later date
+               without overwriting it. This option makes sense only for
+               workloads that write data, and does not support workloads
+               with the time_based option set.
+
 do_verify=bool Run the verify phase after a write phase. Only makes sense if
                verify is set. Defaults to 1.
 
@@ -1077,7 +1113,9 @@ verify=str        If writing to a file, fio can verify the file contents
 
                        meta    Write extra information about each io
                                (timestamp, block number etc.). The block
-                               number is verified. See also verify_pattern.
+                               number is verified. The io sequence number is
+                               verified for workloads that write data.
+                               See also verify_pattern.
 
                        null    Only pretend to verify. Useful for testing
                                internals with ioengine=null, not for much
@@ -1467,7 +1505,9 @@ that defines them is selected.
 [net] proto=str        The network protocol to use. Accepted values are:
 
                        tcp     Transmission control protocol
+                       tcpv6   Transmission control protocol V6
                        udp     User datagram protocol
+                       udpv6   User datagram protocol V6
                        unix    UNIX domain socket
 
                When the protocol is TCP or UDP, the port must also be given,