1.\" Copyright (c) 2013 Edward Tomasz Napierala 2.\" Copyright (c) 2015-2017 Alexander Motin <mav@FreeBSD.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.Dd March 29, 2017 28.Dt CTL 4 29.Os 30.Sh NAME 31.Nm ctl 32.Nd CAM Target Layer 33.Sh SYNOPSIS 34To compile this driver into the kernel, 35place the following line in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device ctl" 39.Ed 40.Pp 41Alternatively, to load the driver as a 42module at boot time, place the following line in 43.Xr loader.conf 5 : 44.Bd -literal -offset indent 45ctl_load="YES" 46.Ed 47.Sh DESCRIPTION 48The 49.Nm 50subsystem provides SCSI target devices emulation. 51It supports features such as: 52.Pp 53.Bl -bullet -compact 54.It 55Disk, CD-ROM and processor device emulation 56.It 57Tagged queueing 58.It 59SCSI task attribute support (ordered, head of queue, simple tags) 60.It 61SCSI implicit command ordering support 62.It 63Full task management support (abort, query, reset, etc.) 64.It 65Support for multiple ports, initiators, targets and backing stores 66.It 67Support for VMWare VAAI and Microsoft ODX offload (COMPARE AND WRITE, 68XCOPY, POPULATE TOKEN/WRITE USING TOKEN, WRITE SAME and UNMAP) 69.It 70Persistent reservation support 71.It 72Extensive VPD/mode/log pages support 73.It 74Featured error reporting, error injection and basic SMART support 75.It 76High Availability clustering support with ALUA 77.It 78All I/O handled in-kernel, no userland context switch overhead 79.El 80.Pp 81The 82.Nm 83subsystem includes multiple frontends to provide access using different 84transport protocols and implementations: 85.Bl -tag -width cfumass 86.It camsim 87Provides access for local system via virtual initiator mode 88.Xr CAM 4 89SIM. 90.It camtgt 91Provides access for remote systems via target mode 92.Xr CAM 4 93SIMs, such as Fibre Channel 94.Xr isp 4 95and 96.Xr mpt 4 . 97.It cfumass 98Provides access for remote systems via USB Mass Storage Class 99Bulk Only (BBB) Transport. 100.It ha 101Internal frontend used to receive requests from other node ports in 102High Availability cluster. 103.It ioctl 104Provides access for local user-level applications via 105.Xr ioctl 2 106based API. 107.It iscsi 108Provides access for remote systems via the iSCSI protocol using 109.Xr cfiscsi 4 . 110.It tpc 111Internal frontend used to receive requests from Third Party Copy engine, 112implementing copy offload operations. 113.El 114.Pp 115The 116.Nm 117subsystem includes two backends to create logical units using different 118kinds of backing stores: 119.Bl -tag -width ramdisk 120.It block 121Stores data in ZFS ZVOLs, files or raw block devices. 122.It ramdisk 123Stores data in RAM, that makes it mostly useful for performance testing. 124Depending on configured capacity can work as black hole, thin or thick 125provisioned disk. 126.El 127.Sh SYSCTL VARIABLES 128The following variables are available as both 129.Xr sysctl 8 130variables and 131.Xr loader 8 132tunables: 133.Bl -tag -width indent 134.It Va kern.cam.ctl.debug 135Bit mask of enabled CTL log levels: 136.Bl -tag -offset indent -compact 137.It 1 138log commands with errors; 139.It 2 140log all commands; 141.It 4 142log data for commands other then READ/WRITE. 143.El 144Defaults to 0. 145.It Va kern.cam.ctl.ha_id 146Specifies unique position of this node within High Availability cluster. 147Default is 0 -- no HA, 1 and 2 -- HA enabled at specified position. 148.It Va kern.cam.ctl.ha_mode 149Specifies High Availability cluster operation mode: 150.Bl -tag -offset indent -compact 151.It 0 152Active/Standby -- primary node has backend access and processes requests, 153while secondary can only do basic LUN discovery and reservation; 154.It 1 155Active/Active -- both nodes have backend access and process requests, 156while secondary node synchronizes processing with primary one; 157.It 2 158Active/Active -- primary node has backend access and processes requests, 159while secondary node forwards all requests and data to primary one; 160.El 161All above modes require established connection between HA cluster nodes. 162If connection is not configured, secondary node will report Unavailable 163state; if configured but not established -- Transitioning state. 164Defaults to 0. 165.It Va kern.cam.ctl.ha_peer 166String value, specifying method to establish connection to peer HA node. 167Can be "listen IP:port", "connect IP:port" or empty. 168.It Va kern.cam.ctl.ha_link 169Reports present state of connection between HA cluster nodes: 170.Bl -tag -offset indent -compact 171.It 0 172not configured; 173.It 1 174configured but not established; 175.It 2 176established. 177.El 178.It Va kern.cam.ctl.ha_role 179Specifies default role of this node: 180.Bl -tag -offset indent -compact 181.It 0 182primary; 183.It 1 184secondary. 185.El 186This role can be overridden on per-LUN basis using "ha_role" LUN option, 187so that for one LUN one node is primary, while for another -- another. 188Role change from primary to secondary for HA modes 0 and 2 closes backends, 189the opposite change -- opens. 190If there is no primary node (both nodes are secondary, or secondary node has 191no connection to primary one), secondary node(s) report Transitioning state. 192State with two primary nodes is illegal (split brain condition). 193.El 194.Sh TUNABLE VARIABLES 195The following variables are available as 196.Xr loader 8 197tunables: 198.Bl -tag -width indent 199.It Va kern.cam.ctl.max_luns 200Specifies the maximum number of LUNs we support, must be a power of 2. 201The default value is 1024. 202.It Va kern.cam.ctl.max_ports 203Specifies the maximum number of ports we support, must be a power of 2. 204The default value is 256. 205.El 206.Sh SEE ALSO 207.Xr cfiscsi 4 , 208.Xr cfumass 4 , 209.Xr ctladm 8 , 210.Xr ctld 8 , 211.Xr ctlstat 8 212.Sh HISTORY 213The 214.Nm 215subsystem first appeared in 216.Fx 9.1 . 217.Sh AUTHORS 218The 219.Nm 220subsystem was originally written by 221.An Kenneth Merry Aq Mt ken@FreeBSD.org . 222Later work was done by 223.An Alexander Motin Aq Mt mav@FreeBSD.org . 224