docs: modify max_open_zones option description

[fio.git] / HOWTO.rst

diff --git a/HOWTO.rst b/HOWTO.rst
index 7ae8ea7b2b6deb8441a6e9deffd50be32a31c79a..7fe70fbdd0ba8425fe759fa2e116ff7e6bb47024 100644 (file)
--- a/HOWTO.rst
+++ b/HOWTO.rst
@@ -1056,22 +1056,34 @@ Target file/device
 
 .. option:: max_open_zones=int
 
-       A zone of a zoned block device is in the open state when it is partially
-       written (i.e. not all sectors of the zone have been written). Zoned
-       block devices may have a limit on the total number of zones that can
-       be simultaneously in the open state, that is, the number of zones that
-       can be written to simultaneously. The :option:`max_open_zones` parameter
-       limits the number of zones to which write commands are issued by all fio
-       jobs, that is, limits the number of zones that will be in the open
-       state. This parameter is relevant only if the :option:`zonemode` =zbd is
-       used. The default value is always equal to maximum number of open zones
-       of the target zoned block device and a value higher than this limit
-       cannot be specified by users unless the option
-       :option:`ignore_zone_limits` is specified. When
-       :option:`ignore_zone_limits` is specified or the target device has no
-       limit on the number of zones that can be in an open state,
-       :option:`max_open_zones` can specify 0 to disable any limit on the
-       number of zones that can be simultaneously written to by all jobs.
+       When a zone of a zoned block device is partially written (i.e. not all
+       sectors of the zone have been written), the zone is in one of three
+       conditions: 'implicit open', 'explicit open' or 'closed'. Zoned block
+       devices may have a limit called 'max_open_zones' (same name as the
+       parameter) on the total number of zones that can simultaneously be in
+       the 'implicit open' or 'explicit open' conditions. Zoned block devices
+       may have another limit called 'max_active_zones', on the total number of
+       zones that can simultaneously be in the three conditions. The
+       :option:`max_open_zones` parameter limits the number of zones to which
+       write commands are issued by all fio jobs, that is, limits the number of
+       zones that will be in the conditions. When the device has the
+       max_open_zones limit and does not have the max_active_zones limit, the
+       :option:`max_open_zones` parameter limits the number of zones in the two
+       open conditions up to the limit. In this case, fio includes zones in the
+       two open conditions to the write target zones at fio start. When the
+       device has both the max_open_zones and the max_active_zones limits, the
+       :option:`max_open_zones` parameter limits the number of zones in the
+       three conditions up to the limit. In this case, fio includes zones in
+       the three conditions to the write target zones at fio start.
+
+       This parameter is relevant only if the :option:`zonemode` =zbd is used.
+       The default value is always equal to the max_open_zones limit of the
+       target zoned block device and a value higher than this limit cannot be
+       specified by users unless the option :option:`ignore_zone_limits` is
+       specified. When :option:`ignore_zone_limits` is specified or the target
+       device does not have the max_open_zones limit, :option:`max_open_zones`
+       can specify 0 to disable any limit on the number of zones that can be
+       simultaneously written to by all jobs.
 
 .. option:: job_max_open_zones=int