1.\" Copyright (c) 2015 The DragonFly BSD Project. 2.\" All rights reserved. 3.\" 4.\" This code is derived from software contributed to The DragonFly BSD Project 5.\" by Tomohiro Kusumi <kusumi.tomohiro@gmail.com> 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26.\" POSSIBILITY OF SUCH DAMAGE. 27.Dd October 11, 2015 28.Dt DM_TARGET_DELAY 4 29.Os 30.Sh NAME 31.Nm dm_target_delay 32.Nd Device-mapper delay target 33.Sh SYNOPSIS 34To compile this driver into the kernel, 35place the following lines in your 36kernel configuration file: 37.Bd -ragged -offset indent 38.Cd "device dm" 39.Cd "device dm_target_delay" 40.Ed 41.Pp 42Alternatively, to load the driver as a 43module at boot time, place the following line in 44.Xr loader.conf 5 : 45.Bd -literal -offset indent 46dm_target_delay_load="YES" 47.Ed 48.Sh DESCRIPTION 49The 50.Nm 51target for 52.Xr dm 4 53provides I/O delay for read or both read and write, and maps them to 54specified devices, compatible with Linux dm-delay. 55.Dq Nm dmsetup Cm create 56takes the following list of parameters for the 57.Nm 58table. 59.Bd -ragged -offset indent 60.Cd "<read_device> <read_offset> <read_delay> [<write_device> <write_offset> <write_delay>]" 61.Ed 62.Pp 63Parameters for write delay are optional. 64If write parameters are not specified, read parameters are used for write. 65In order to only delay read, explicitly specify 0 delay for write. 66.Pp 67Offsets are specified in 512 bytes sectors. 68Delays are specified in milliseconds. 69.Sh SEE ALSO 70.Xr dm 4 , 71.Xr dmsetup 8 72.Sh HISTORY 73The 74.Nm 75.Xr dm 4 76target first appeared in 77.Dx 4.3 . 78.Sh AUTHORS 79.An Tomohiro Kusumi 80