1.\" $NetBSD: fssconfig.8,v 1.12 2016/07/29 05:20:33 pgoyette Exp $ */ 2.\" 3.\" 4.\" Copyright (c) 2003 The NetBSD Foundation, Inc. 5.\" All rights reserved. 6.\" 7.\" This code is derived from software contributed to The NetBSD Foundation 8.\" by Juergen Hannken-Illjes. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29.\" POSSIBILITY OF SUCH DAMAGE. 30.\" 31.Dd July 29, 2016 32.Dt FSSCONFIG 8 33.Os 34.Sh NAME 35.Nm fssconfig 36.Nd configure file system snapshot devices 37.Sh SYNOPSIS 38.Nm 39.Op Fl cxv 40.Ar device 41.Ar path 42.Ar backup 43.Op Ar cluster Op Ar size 44.Nm 45.Fl u Op Fl v 46.Ar device 47.Nm 48.Fl l Op Fl v 49.Op Ar device 50.Sh DESCRIPTION 51The 52.Nm 53command configures file system snapshot pseudo disk devices. 54It will associate the file system snapshot disk 55.Ar device 56with a snapshot of the file system mounted on 57.Ar path , 58allowing 59.Ar device 60to be accessed as though it were a disk. 61.Pp 62If 63.Ar backup 64resides on the snapshotted file system a persistent snapshot will be created. 65This snapshot is active until 66.Ar backup 67is unlinked. 68Persistent snapshots save the file system as if it had been unmounted. 69Unlinked but open files get removed from the snapshot. 70The time needed to create a persistent snapshot increases with the size of the 71file system and decreases with the file system block size. 72This snapshot mode is only supported for FFS file systems. 73.Pp 74Otherwise data written through the 75.Ar path 76will be saved in 77.Ar backup . 78If 79.Ar backup 80is a regular file, it will be created with length 81.Ar size . 82Default size is the size of 83.Ar path . 84Data is saved to 85.Ar backup 86in units of 87.Ar cluster 88bytes. 89The snapshot is an image of the underlying block device at a moment in time. 90Unlinked but open files are still present on the snapshot. 91The time needed to create a snapshot is independent of the size of the 92file system or the file system block size. 93.Pp 94Options indicate an action to be performed: 95.Bl -tag -width 3n 96.It Fl c 97Configures the device. 98If successful, references to 99.Ar device 100will access the contents of 101.Ar path 102at the time the snapshot was taken. 103If 104.Ar backup 105is a directory, a temporary file will be created in this directory. 106This file will be unlinked on exit. 107.It Fl l 108List the snapshot devices and indicate which ones are in use. 109If a specific 110.Ar device 111is given, then only that will be described. 112.It Fl u 113Unconfigures the 114.Ar device . 115.It Fl v 116Be more verbose listing the snapshot devices. 117.It Fl x 118Unlink 119.Ar backup 120after the 121.Ar device 122is configured. 123.El 124.Pp 125If no action option is given, 126.Fl c 127is assumed. 128.Sh FILES 129.Bl -tag -width /etc/disktab -compact 130.It Pa /dev/rfss? 131.It Pa /dev/fss? 132.El 133.Sh EXAMPLES 134.Dl fssconfig fss0 /usr /tmp/back 135.Dl mount /dev/fss0 /mnt 136.Pp 137Configures the snapshot device 138.Pa fss0 139as a snapshot of the 140.Pa /usr 141file system, and makes the contents of the snapshot available via 142.Pa /mnt . 143Data written through 144.Pa /usr 145will be backed up in 146.Pa /tmp/back . 147.Pp 148.Dl fssconfig fss1 / /dev/rsd0e 8192 149.Pp 150Configures the snapshot device 151.Pa fss1 152as a snapshot of the 153.Pa / 154file system. 155Data written through 156.Pa / 157will be backed up in 158.Pa /dev/rsd0e . 159The backup will take place in units of 8192 bytes. 160.Pp 161.Dl fssconfig -u fss0 162.Pp 163Unconfigures the 164.Pa fss0 165device. 166.Sh SEE ALSO 167.Xr opendisk 3 , 168.Xr fss 4 , 169.Xr dump 8 , 170.Xr mount 8 , 171.Xr umount 8 172.Sh HISTORY 173The 174.Nm 175command appeared in 176.Nx 2.0 . 177