Add support for zoned block devices

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index a0fadcbbd52359c24d65f3641d09c4fa5697b069..b7e18529749b16fc607db18fe7f250668eafe050 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -997,6 +997,26 @@ Target file/device
        :option:`zonesize` bytes of data have been transferred. This parameter
        must be zero for :option:`zonemode` =zbd.
 
+.. option:: read_beyond_wp=bool
+
+       This parameter applies to :option:`zonemode` =zbd only.
+
+       Zoned block devices are block devices that consist of multiple zones.
+       Each zone has a type, e.g. conventional or sequential. A conventional
+       zone can be written at any offset that is a multiple of the block
+       size. Sequential zones must be written sequentially. The position at
+       which a write must occur is called the write pointer. A zoned block
+       device can be either drive managed, host managed or host aware. For
+       host managed devices the host must ensure that writes happen
+       sequentially. Fio recognizes host managed devices and serializes
+       writes to sequential zones for these devices.
+
+       If a read occurs in a sequential zone beyond the write pointer then
+       the zoned block device will complete the read without reading any data
+       from the storage medium. Since such reads lead to unrealistically high
+       bandwidth and IOPS numbers fio only reads beyond the write pointer if
+       explicitly told to do so. Default: false.
+
 
 I/O type
 ~~~~~~~~