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diff --git a/static/freebsd/man4/nda.4 b/static/freebsd/man4/nda.4 new file mode 100644 index 00000000..e45b2905 --- /dev/null +++ b/static/freebsd/man4/nda.4 @@ -0,0 +1,215 @@ +.\" +.\" SPDX-License-Identifier: BSD-2-Clause +.\" +.\" Copyright (c) 2017 Netflix, Inc. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.Dd October 2, 2025 +.Dt NDA 4 +.Os +.Sh NAME +.Nm nda +.Nd NVMe Direct Access device driver +.Sh SYNOPSIS +.Cd device nvme +.Cd device scbus +.Sh DESCRIPTION +The +.Nm +driver provides support for direct access devices, implementing the +.Tn NVMe +command protocol, that are attached to the system through a host adapter +supported by the CAM subsystem. +.Sh HARDWARE +The +.Nm +driver supports NVMe +.Pq Non-Volatile Memory Express +storage devices connected via PCIe or over NVMF +.Pq NVMe over Fabric +via the CAM subsystem. +.Sh SYSCTL VARIABLES +The following variables are available as both +.Xr sysctl 8 +variables and +.Xr loader 8 +tunables: +.Bl -tag -width 12 +.It Va hw.nvme.use_nvd +The +.Xr nvme 4 +driver will create +.Nm +device nodes for block storage when set to 0. +Create +.Xr nvd 4 +device nodes for block storage when set to 1. +See +.Xr nvd 4 +when set to 1. +.It Va kern.cam.nda.nvd_compat +When set to 1, +.Xr nvd 4 +aliases will be created for all +.Nm +devices, including partitions and other +.Xr geom 4 +providers that take their names from the disk's name. +.Xr nvd 4 +devices will not, however, be reported in the +.Va kern.disks +.Xr sysctl 8 . +.It Va kern.cam.nda.sort_io_queue +This variable determines whether the software queued entries are +sorted in LBA order or not. +Sorting is almost always a waste of time. +The default is to not sort. +.It Va kern.cam.nda.enable_biospeedup +This variable determines if the +.Nm +devices participate in the speedup protocol. +When the device participates in the speedup, then when the upper layers +send a +.Va BIO_SPEEDUP , +all current +.Va BIO_DELETE +requests not yet sent to the hardware are completed successfully immediate +without sending them to the hardware. +Used in low disk space scenarios when the filesystem encounters +a critical shortage and needs blocks immediately. +Since trims have maximum benefit when the LBA is unused for a long time, +skipping the trim when space is needed for immediate writes results in little to +no excess wear. +When participation is disabled, +.Va BIO_SPEEDUP +requests are ignored. +.It Va kern.cam.nda.max_trim +The maximum number of LBA ranges to be collected together for each DSM trims +send to the hardware. +Defaults to 256, which is the maximum number of ranges the protocol supports. +Sometimes poor trim performance can be mitigated by limiting the number of +ranges sent to the device. +This value must be between 1 and 256 inclusive. +.El +.Pp +The following report per-device settings, and are read-only unless +otherwise indicated. +Replace +.Va N +with the device unit number. +.Bl -tag -width 12 +.It Va kern.cam.nda.N.rotating +This variable reports whether the storage volume is spinning or +flash. +Its value is hard coded to 0 indicating flash. +.It Va kern.cam.nda.N.unmapped_io +This variable reports whether the +.Nm +driver accepts unmapped I/O for this unit. +.It Va kern.cam.nda.N.flags +This variable reports the current flags. +.Bl -tag -width 12 +.It Va OPEN +The device is open. +.It Va DIRTY +Set when a write to the drive is scheduled. +Cleared after flush commands. +.It Va SCTX_INIT +Internal flag set after +.Xr sysctl 8 +nodes have been created. +.El +.It Va kern.cam.nda.N.sort_io_queue +Same as the +.Va kern.cam.nda.sort_io_queue +tunable. +.It Va kern.cam.nda.N.trim_ticks +Writable. +When greater than zero, hold trims for up to this many ticks before sending +to the drive. +Sometimes waiting a little bit to collect more trims to send at one time +improves trim performance. +When 0, no delaying of trims are done. +.It Va kern.cam.nda.N.trim_goal +Writable. +When delaying a bit to collect multiple trims, send the accumulated DSM TRIM to +the drive. +.It Va kern.cam.nda.N.trim_lbas +Total number of LBAs that have been trimmed. +.It Va kern.cam.nda.N.trim_ranges +Total number of LBA ranges that have been trimmed. +.It Va kern.cam.nda.N.trim_count +Total number of trims sent to the hardware. +.It Va kern.cam.nda.N.deletes +Total number of +.Va BIO_DELETE +requests queued to the device. +.El +.Sh NAMESPACE MAPPING +Each +.Xr nvme 4 +drive has one or more namespaces associated with it. +One instance of the +.Nm +driver will be created for each of the namespaces on +the drive. +All the +.Nm +nodes for a +.Xr nvme 4 +device are at target 0. +However, the namespace ID maps to the CAM lun, as reported +in kernel messages and in the +.Va devlist +sub command of +.Xr camcontrol 8 . +.Pp +Namespaces are managed with the +.Va ns +sub command of +.Xr nvmecontrol 8 . +Not all drives support namespace management, +but all drives support at least one namespace. +Device nodes for +.Nm +will be created and destroyed dynamically as +namespaces are activated or detached. +.Sh FILES +.Bl -tag -width ".Pa /dev/nda*" -compact +.It Pa /dev/nda* +NVMe storage device nodes +.El +.Sh SEE ALSO +.Xr cam 4 , +.Xr geom 4 , +.Xr nvd 4 , +.Xr nvme 4 , +.Xr gpart 8 +.Sh HISTORY +The +.Nm +driver first appeared in +.Fx 12.0 . +.Sh AUTHORS +.An Warner Losh Aq Mt imp@FreeBSD.org |