Define OS preferred IO engine

[fio.git] / fio.1

diff --git a/fio.1 b/fio.1
index f01bf3a4faa9ef4a50aeb80dac3658c545eb356c..d372727b69e7311d095ced198c2855f66091ec3d 100644 (file)
--- a/fio.1
+++ b/fio.1
@@ -226,7 +226,7 @@ are likely to be issued. Default: true.
 .BI size \fR=\fPint
 Total size of I/O for this job.  \fBfio\fR will run until this many bytes have
 been transfered, unless limited by other options (\fBruntime\fR, for instance).
-Unless \fBnr_files\fR and \fBfilesize\fR options are given, this amount will be
+Unless \fBnrfiles\fR and \fBfilesize\fR options are given, this amount will be
 divided between the available files for the job. If not set, fio will use the
 full size of the given files or devices. If the the files do not exist, size
 must be given.
@@ -331,7 +331,13 @@ coalescing adjacents IOs into a single submission.
 Linux native asynchronous I/O.
 .TP
 .B posixaio
-glibc POSIX asynchronous I/O using \fIaio_read\fR\|(3) and \fIaio_write\fR\|(3).
+POSIX asynchronous I/O using \fIaio_read\fR\|(3) and \fIaio_write\fR\|(3).
+.TP
+.B solarisaio
+Solaris native asynchronous I/O.
+.TP
+.B windowsaio
+Windows native asynchronous I/O.
 .TP
 .B mmap
 File is memory mapped with \fImmap\fR\|(2) and data copied using
@@ -379,7 +385,13 @@ Loads an external I/O engine object file.  Append the engine filename as
 .RE
 .TP
 .BI iodepth \fR=\fPint
-Number of I/O units to keep in flight against the file.  Default: 1.
+Number of I/O units to keep in flight against the file. Note that increasing
+iodepth beyond 1 will not affect synchronous ioengines (except for small
+degress when verify_async is in use). Even async engines my impose OS
+restrictions causing the desired depth not to be achieved.  This may happen on
+Linux when using libaio and not setting \fBdirect\fR=1, since buffered IO is
+not async on that OS. Keep an eye on the IO depth distribution in the
+fio output to verify that the achieved depth is as expected. Default: 1.
 .TP
 .BI iodepth_batch \fR=\fPint
 Number of I/Os to submit at once.  Default: \fBiodepth\fR.
@@ -680,6 +692,11 @@ has to be a hex number that starts with either "0x" or "0X". Use with
 If true, exit the job on the first observed verification failure.  Default:
 false.
 .TP
+.BI verify_dump \fR=\fPbool
+If set, dump the contents of both the original data block and the data block we
+read off disk to files. This allows later analysis to inspect just what kind of
+data corruption occurred. On by default.
+.TP
 .BI verify_async \fR=\fPint
 Fio will normally verify IO inline from the submitting thread. This option
 takes an integer describing how many async offload threads to create for IO
@@ -737,7 +754,9 @@ Skip the specified number of bytes when \fBzonesize\fR bytes of data have been
 read.
 .TP
 .BI write_iolog \fR=\fPstr
-Write the issued I/O patterns to the specified file.
+Write the issued I/O patterns to the specified file.  Specify a separate file
+for each job, otherwise the iologs will be interspersed and the file may be
+corrupt.
 .TP
 .BI read_iolog \fR=\fPstr
 Replay the I/O patterns contained in the specified file generated by