docs: add documentation for sg ioengine WRITE SAME, WRITE AND VERIFY command support

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index c34fdf32986fc1f8ae3ed0ec475a2ee7135118f5..7680f9c7634a7e55044dba0a8ebdc6928fb3bfc0 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -2079,6 +2079,26 @@ with the caveat that when used on the command line, they must come after the
        With writefua option set to 1, write operations include
        the force unit access (fua) flag. Default is 0.
 
        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
 ~~~~~~~~~
 
 I/O depth
 ~~~~~~~~~


@@ -2346,6 +2366,14 @@ I/O replay
 
        Scale sector offsets down by this factor when replaying traces.
 
 
        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
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Threads, processes and job synchronization
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


@@ -2635,18 +2663,6 @@ Verification
        previously written file. If the data direction includes any form of write,
        the verify will be of the newly written data.
 
        previously written file. If the data direction includes any form of write,
        the verify will be of the newly written data.
 

-.. option:: verifysort=bool
-
-       If true, fio will sort written verify blocks when it deems it faster to read
-       them back in a sorted manner. This is often the case when overwriting an
-       existing file, since the blocks are already laid out in the file system. You
-       can ignore this option unless doing huge amounts of really fast I/O where
-       the red-black tree sorting CPU time becomes significant. Default: true.
-
-.. option:: verifysort_nr=int
-
-       Pre-load and sort verify blocks for a read workload.
-

 .. option:: verify_offset=int
 
        Swap the verification header with data somewhere else in the block before
 .. option:: verify_offset=int
 
        Swap the verification header with data somewhere else in the block before