@@ -286,4 +286,35 @@ sequential zones of zoned block devices (devices with a zoned attributed
that reports "host-managed" or "host-aware"). This value is always 0 for
regular block devices.
+independent_access_ranges (RO)
+------------------------------
+
+The presence of this sub-directory of the /sys/block/xxx/queue/ directory
+indicates that the device is capable of executing requests targeting
+different sector ranges in parallel. For instance, single LUN multi-actuator
+hard-disks will have an independent_access_ranges directory if the device
+correctly advertizes the sector ranges of its actuators.
+
+The independent_access_ranges directory contains one directory per access
+range, with each range described using the sector (RO) attribute file to
+indicate the first sector of the range and the nr_sectors (RO) attribute file
+to indicate the total number of sectors in the range starting from the first
+sector of the range. For example, a dual-actuator hard-disk will have the
+following independent_access_ranges entries.::
+
+ $ tree /sys/block/<device>/queue/independent_access_ranges/
+ /sys/block/<device>/queue/independent_access_ranges/
+ |-- 0
+ | |-- nr_sectors
+ | `-- sector
+ `-- 1
+ |-- nr_sectors
+ `-- sector
+
+The sector and nr_sectors attributes use 512B sector unit, regardless of
+the actual block size of the device. Independent access ranges do not
+overlap and include all sectors within the device capacity. The access
+ranges are numbered in increasing order of the range start sector,
+that is, the sector attribute of range 0 always has the value 0.
+
Jens Axboe <jens.axboe@oracle.com>, February 2009
Update the file Documentation/block/queue-sysfs.rst to add a description of a device queue sysfs entries related to independent access ranges (e.g. concurrent positioning ranges for multi-actuator hard-disks). Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> --- Documentation/block/queue-sysfs.rst | 31 +++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)