Add fill_fs alias for fill_device

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 35dccfb16855683115e62ff83109fa9b886f5407..d4e70923facf5b0b3ed322a551bee9a445fc3046 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -351,7 +351,8 @@ randrepeat=bool     For random IO workloads, seed the generator in a predictable
 fallocate=bool By default, fio will use fallocate() to advise the system
                of the size of the file we are going to write. This can be
                turned off with fallocate=0. May not be available on all
-               supported platforms.
+               supported platforms.  If using ZFS on Solaris this must be
+               set to 0 because ZFS doesn't support it.
 
 fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
                on what IO patterns it is likely to issue. Sometimes you
@@ -374,10 +375,15 @@ filesize=int      Individual file sizes. May be a range, in which case fio
                and limited to 'size' in total (if that is given). If not
                given, each created file is the same size.
 
-fill_device=bool Sets size to something really large and waits for ENOSPC (no
+fill_device=bool
+fill_fs=bool   Sets size to something really large and waits for ENOSPC (no
                space left on device) as the terminating condition. Only makes
                 sense with sequential write. For a read workload, the mount
-               point will be filled first then IO started on the result.
+               point will be filled first then IO started on the result. This
+               option doesn't make sense if operating on a raw device node,
+               since the size of that is already known by the file system.
+               Additionally, writing beyond end-of-device will not return
+               ENOSPC there.
 
 blocksize=int
 bs=int         The block size used for the io units. Defaults to 4k. Values
@@ -555,7 +561,7 @@ iodepth=int This defines how many io units to keep in flight against
                job, can be overridden with a larger value for higher
                concurrency. 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
+               verify_async is in use). Even async engines may impose OS
                restrictions causing the desired depth not to be achieved.
                This may happen on Linux when using libaio and not setting
                direct=1, since buffered IO is not async on that OS. Keep an
@@ -585,7 +591,7 @@ iodepth_low=int     The low water mark indicating when to start filling
                the depth drain down to 4 before starting to fill it again.
 
 direct=bool    If value is true, use non-buffered io. This is usually
-               O_DIRECT.
+               O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
 
 buffered=bool  If value is true, use buffered io. This is the opposite
                of the 'direct' option. Defaults to true.
@@ -925,6 +931,11 @@ verify_fatal=bool  Normally fio will keep checking the entire contents
                option is set, fio will exit the job on the first observed
                failure.
 
+verify_dump=bool       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.
+
 verify_async=int       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 verification instead,
@@ -992,7 +1003,8 @@ zoneskip=int       Skip the specified number of bytes when zonesize data has
                io on zones of a file.
 
 write_iolog=str        Write the issued io patterns to the specified file. See
-               read_iolog.
+               read_iolog.  Specify a separate file for each job, otherwise
+               the iologs will be interspersed and the file may be corrupt.
 
 read_iolog=str Open an iolog with the specified file name and replay the
                io patterns it contains. This can be used to store a