Add support for absolute random zones

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 164ba2bbdea245a63470cb8009a72904366d3959..dc99e9989a47a262cc432ef8f5507acd6e54c85a 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -1254,6 +1254,9 @@ I/O type
                **zoned**
                                Zoned random distribution
 
+               **zoned_abs**
+                               Zone absolute random distribution
+
        When using a **zipf** or **pareto** distribution, an input value is also
        needed to define the access pattern. For **zipf**, this is the `Zipf
        theta`. For **pareto**, it's the `Pareto power`. Fio includes a test
@@ -1278,10 +1281,23 @@ I/O type
 
                random_distribution=zoned:60/10:30/20:8/30:2/40
 
-       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 is given, it'll apply to
-       all of them.
+       A **zoned_abs** distribution works exactly like the **zoned**, except
+       that it takes absolute sizes. For example, let's say you wanted to
+       define access according to the following criteria:
+
+               * 60% of accesses should be to the first 20G
+               * 30% of accesses should be to the next 100G
+               * 10% of accesses should be to the next 500G
+
+       we can define an absolute zoning distribution with:
+
+               random_distribution=zoned_abs=60/20G:30/100G:10/500g
+
+       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
+       is given, it'll apply to all of them. This goes for both **zoned**
+       **zoned_abs** distributions.
 
 .. option:: percentage_random=int[,int][,int]