Collect a block-wise histogram of trim and write errors

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 8da5527a3edb6cbfd408f497260651d99c633be0..6c7abcc7979d275a0bea276fd09deae69a587fec 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -460,6 +460,10 @@ fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
                If set, fio will use POSIX_FADV_SEQUENTIAL for sequential
                IO and POSIX_FADV_RANDOM for random IO.
 
+fadvise_stream=int Notify the kernel what write stream ID to place these
+               writes under. Only supported on Linux. Note, this option
+               may change going forward.
+
 size=int       The total size of file io for this job. Fio will run until
                this many bytes has been transferred, unless runtime is
                limited by other options (such as 'runtime', for instance,
@@ -578,8 +582,6 @@ bs_is_seq_rand      If this option is set, fio will use the normal read,write
 
 zero_buffers   If this option is given, fio will init the IO buffers to
                all zeroes. The default is to fill them with random data.
-               The resulting IO buffers will not be completely zeroed,
-               unless scramble_buffers is also turned off.
 
 refill_buffers If this option is given, fio will refill the IO buffers
                on every submit. The default is to only fill it at init
@@ -919,10 +921,10 @@ norandommap       Normally fio will cover every block of the file when doing
                random IO. If this option is given, fio will just get a
                new random offset without looking at past io history. This
                means that some blocks may not be read or written, and that
-               some blocks may be read/written more than once. This option
-               is mutually exclusive with verify= if and only if multiple
-               blocksizes (via bsrange=) are used, since fio only tracks
-               complete rewrites of blocks.
+               some blocks may be read/written more than once. If this option
+               is used with verify= and multiple blocksizes (via bsrange=),
+               only intact blocks are verified, i.e., partially-overwritten
+               blocks are ignored.
 
 softrandommap=bool See norandommap. If fio runs with the random block map
                enabled and it fails to allocate the map, if this option is
@@ -1466,6 +1468,11 @@ log_store_compressed=bool        If set, and log_compression is also set,
                command line parameter. The files will be stored with a
                .fz suffix.
 
+block_error_percentiles=bool   If set, record errors in trim block-sized
+               units from writes and trims and output a histogram of
+               how many trims it took to get to errors, and what kind
+               of error was encountered.
+
 lockmem=int    Pin down the specified amount of memory with mlock(2). Can
                potentially be used instead of removing memory or booting
                with less memory to simulate a smaller amount of memory.
@@ -1505,13 +1512,13 @@ clat_percentiles=bool Enable the reporting of percentiles of
                 completion latencies.
 
 percentile_list=float_list Overwrite the default list of percentiles
-               for completion latencies. Each number is a floating
-               number in the range (0,100], and the maximum length of
-               the list is 20. Use ':' to separate the numbers, and
-               list the numbers in ascending order. For example,
-               --percentile_list=99.5:99.9 will cause fio to report
-               the values of completion latency below which 99.5% and
-               99.9% of the observed latencies fell, respectively.
+               for completion latencies and the block error histogram.
+               Each number is a floating number in the range (0,100],
+               and the maximum length of the list is 20. Use ':'
+               to separate the numbers, and list the numbers in ascending
+               order. For example, --percentile_list=99.5:99.9 will cause
+               fio to report the values of completion latency below which
+               99.5% and 99.9% of the observed latencies fell, respectively.
 
 clocksource=str        Use the given clocksource as the base of timing. The
                supported options are: