0acc026dda
SAM-5 specification states maximum size of command identifier (tag), defined by specific transports, should not be larger than 64 bits. While most of supported transports use 32 bits or less, it was reported that virtio-scsi uses 64 bits. Truncation to 32 bits in bhyve code caused false tag conflict errors reported and possibly other issues. This changes CTL ABI and HA protocol, so CTL_HA_VERSION is bumped. While we make HA protocol incompatible, increase default maximum number of ports in CTL from 256 to 1024, matching number of LUNs. There are many reports from people who need many iSCSI targets with only one LUN each. Increased memory consumption should be less of a problem these days. PR: 267539
224 lines
6.7 KiB
Groff
224 lines
6.7 KiB
Groff
.\" Copyright (c) 2013 Edward Tomasz Napierala
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.\" Copyright (c) 2015-2017 Alexander Motin <mav@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.Dd March 29, 2017
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.Dt CTL 4
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.Os
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.Sh NAME
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.Nm ctl
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.Nd CAM Target Layer
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.Sh SYNOPSIS
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To compile this driver into the kernel,
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place the following line in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device ctl"
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.Ed
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.Pp
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Alternatively, to load the driver as a
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module at boot time, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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ctl_load="YES"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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subsystem provides SCSI target devices emulation.
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It supports features such as:
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.Pp
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.Bl -bullet -compact
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.It
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Disk, CD-ROM and processor device emulation
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.It
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Tagged queueing
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.It
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SCSI task attribute support (ordered, head of queue, simple tags)
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.It
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SCSI implicit command ordering support
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.It
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Full task management support (abort, query, reset, etc.)
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.It
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Support for multiple ports, initiators, targets and backing stores
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.It
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Support for VMWare VAAI and Microsoft ODX offload (COMPARE AND WRITE,
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XCOPY, POPULATE TOKEN/WRITE USING TOKEN, WRITE SAME and UNMAP)
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.It
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Persistent reservation support
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.It
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Extensive VPD/mode/log pages support
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.It
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Featured error reporting, error injection and basic SMART support
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.It
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High Availability clustering support with ALUA
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.It
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All I/O handled in-kernel, no userland context switch overhead
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.El
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.Pp
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The
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.Nm
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subsystem includes multiple frontends to provide access using different
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transport protocols and implementations:
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.Bl -tag -width cfumass
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.It camsim
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Provides access for local system via virtual initiator mode
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.Xr CAM 4
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SIM.
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.It camtgt
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Provides access for remote systems via target mode
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.Xr CAM 4
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SIMs, such as Fibre Channel
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.Xr isp 4
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and
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.Xr mpt 4 .
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.It cfumass
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Provides access for remote systems via USB Mass Storage Class
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Bulk Only (BBB) Transport.
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.It ha
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Internal frontend used to receive requests from other node ports in
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High Availability cluster.
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.It ioctl
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Provides access for local user-level applications via
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.Xr ioctl 2
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based API.
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.It iscsi
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Provides access for remote systems via the iSCSI protocol using
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.Xr cfiscsi 4 .
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.It tpc
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Internal frontend used to receive requests from Third Party Copy engine,
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implementing copy offload operations.
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.El
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.Pp
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The
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.Nm
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subsystem includes two backends to create logical units using different
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kinds of backing stores:
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.Bl -tag -width ramdisk
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.It block
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Stores data in ZFS ZVOLs, files or raw block devices.
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.It ramdisk
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Stores data in RAM, that makes it mostly useful for performance testing.
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Depending on configured capacity can work as black hole, thin or thick
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provisioned disk.
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.El
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.Sh SYSCTL VARIABLES
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The following variables are available as both
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.Xr sysctl 8
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variables and
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.Xr loader 8
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tunables:
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.Bl -tag -width indent
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.It Va kern.cam.ctl.debug
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Bit mask of enabled CTL log levels:
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.Bl -tag -offset indent -compact
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.It 1
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log commands with errors;
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.It 2
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log all commands;
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.It 4
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log data for commands other then READ/WRITE.
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.El
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Defaults to 0.
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.It Va kern.cam.ctl.ha_id
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Specifies unique position of this node within High Availability cluster.
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Default is 0 -- no HA, 1 and 2 -- HA enabled at specified position.
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.It Va kern.cam.ctl.ha_mode
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Specifies High Availability cluster operation mode:
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.Bl -tag -offset indent -compact
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.It 0
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Active/Standby -- primary node has backend access and processes requests,
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while secondary can only do basic LUN discovery and reservation;
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.It 1
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Active/Active -- both nodes have backend access and process requests,
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while secondary node synchronizes processing with primary one;
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.It 2
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Active/Active -- primary node has backend access and processes requests,
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while secondary node forwards all requests and data to primary one;
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.El
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All above modes require established connection between HA cluster nodes.
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If connection is not configured, secondary node will report Unavailable
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state; if configured but not established -- Transitioning state.
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Defaults to 0.
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.It Va kern.cam.ctl.ha_peer
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String value, specifying method to establish connection to peer HA node.
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Can be "listen IP:port", "connect IP:port" or empty.
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.It Va kern.cam.ctl.ha_link
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Reports present state of connection between HA cluster nodes:
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.Bl -tag -offset indent -compact
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.It 0
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not configured;
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.It 1
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configured but not established;
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.It 2
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established.
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.El
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.It Va kern.cam.ctl.ha_role
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Specifies default role of this node:
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.Bl -tag -offset indent -compact
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.It 0
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primary;
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.It 1
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secondary.
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.El
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This role can be overridden on per-LUN basis using "ha_role" LUN option,
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so that for one LUN one node is primary, while for another -- another.
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Role change from primary to secondary for HA modes 0 and 2 closes backends,
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the opposite change -- opens.
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If there is no primary node (both nodes are secondary, or secondary node has
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no connection to primary one), secondary node(s) report Transitioning state.
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State with two primary nodes is illegal (split brain condition).
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.El
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.Sh TUNABLE VARIABLES
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The following variables are available as
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.Xr loader 8
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tunables:
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.Bl -tag -width indent
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.It Va kern.cam.ctl.max_luns
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Specifies the maximum number of LUNs we support, must be a power of 2.
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The default value is 1024.
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.It Va kern.cam.ctl.max_ports
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Specifies the maximum number of ports we support, must be a power of 2.
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The default value is 1024.
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.El
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.Sh SEE ALSO
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.Xr cfiscsi 4 ,
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.Xr cfumass 4 ,
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.Xr ctladm 8 ,
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.Xr ctld 8 ,
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.Xr ctlstat 8
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.Sh HISTORY
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The
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.Nm
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subsystem first appeared in
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.Fx 9.1 .
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.Sh AUTHORS
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The
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.Nm
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subsystem was originally written by
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.An Kenneth Merry Aq Mt ken@FreeBSD.org .
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Later work was done by
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.An Alexander Motin Aq Mt mav@FreeBSD.org .
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