Documentation: add note about how many bssplit and zones fio supports

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index dc99e9989a47a262cc432ef8f5507acd6e54c85a..4caaf542e0e4b89f4156309469e476700f4b372f 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -1293,6 +1293,9 @@ I/O type
 
                random_distribution=zoned_abs=60/20G:30/100G:10/500g
 
+       For both **zoned** and **zoned_abs**, fio supports defining up to
+       256 separate zones.
+
        Similarly to how :option:`bssplit` works for setting ranges and
        percentages of block sizes. Like :option:`bssplit`, it's possible to
        specify separate zones for reads, writes, and trims. If just one set
@@ -1388,34 +1391,39 @@ Block size
 
 .. option:: bssplit=str[,str][,str]
 
-       Sometimes you want even finer grained control of the block sizes issued, not
-       just an even split between them.  This option allows you to weight various
-       block sizes, so that you are able to define a specific amount of block sizes
-       issued. The format for this option is::
+       Sometimes you want even finer grained control of the block sizes
+       issued, not just an even split between them.  This option allows you to
+       weight various block sizes, so that you are able to define a specific
+       amount of block sizes issued. The format for this option is::
 
                bssplit=blocksize/percentage:blocksize/percentage
 
-       for as many block sizes as needed. So if you want to define a workload that
-       has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would write::
+       for as many block sizes as needed. So if you want to define a workload
+       that has 50% 64k blocks, 10% 4k blocks, and 40% 32k blocks, you would
+       write::
 
                bssplit=4k/10:64k/50:32k/40
 
-       Ordering does not matter. If the percentage is left blank, fio will fill in
-       the remaining values evenly. So a bssplit option like this one::
+       Ordering does not matter. If the percentage is left blank, fio will
+       fill in the remaining values evenly. So a bssplit option like this one::
 
                bssplit=4k/50:1k/:32k/
 
-       would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always add up
-       to 100, if bssplit is given a range that adds up to more, it will error out.
+       would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always
+       add up to 100, if bssplit is given a range that adds up to more, it
+       will error out.
 
        Comma-separated values may be specified for reads, writes, and trims as
        described in :option:`blocksize`.
 
-       If you want a workload that has 50% 2k reads and 50% 4k reads, while having
-       90% 4k writes and 10% 8k writes, you would specify::
+       If you want a workload that has 50% 2k reads and 50% 4k reads, while
+       having 90% 4k writes and 10% 8k writes, you would specify::
 
                bssplit=2k/50:4k/50,4k/90,8k/10
 
+       Fio supports defining up to 64 different weights for each data
+       direction.
+
 .. option:: blocksize_unaligned, bs_unaligned
 
        If set, fio will issue I/O units with any size within
@@ -2950,20 +2958,20 @@ Measurements and reporting
 
 .. option:: percentile_list=float_list
 
-       Overwrite the default list of percentiles 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.
+       Overwrite the default list of percentiles 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.
 
 .. option:: significant_figures=int
 
-       If using :option:`--output-format` of `normal`, set the significant figures 
-       to this value. Higher values will yield more precise IOPS and throughput 
-       units, while lower values will round. Requires a minimum value of 1 and a 
-       maximum value of 10. Defaults to 4.
+       If using :option:`--output-format` of `normal`, set the significant
+       figures to this value. Higher values will yield more precise IOPS and
+       throughput units, while lower values will round. Requires a minimum
+       value of 1 and a maximum value of 10. Defaults to 4.
 
 
 Error handling