1.\" 2.\" Copyright (c) 2003 Networks Associates Technology, Inc. 3.\" All rights reserved. 4.\" 5.\" This software was developed for the FreeBSD Project by Marshall 6.\" Kirk McKusick and Network Associates Laboratories, the Security 7.\" Research Division of Network Associates, Inc. under DARPA/SPAWAR 8.\" contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS 9.\" research program. 10.\" 11.\" Redistribution and use in source and binary forms, with or without 12.\" modification, are permitted provided that the following conditions 13.\" are met: 14.\" 1. Redistributions of source code must retain the above copyright 15.\" notice, this list of conditions and the following disclaimer. 16.\" 2. Redistributions in binary form must reproduce the above copyright 17.\" notice, this list of conditions and the following disclaimer in the 18.\" documentation and/or other materials provided with the distribution. 19.\" 3. The names of the authors may not be used to endorse or promote 20.\" products derived from this software without specific prior written 21.\" permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" $FreeBSD$ 36.\" 37.Dd October 3, 2016 38.Dt MKSNAP_FFS 8 39.Os 40.Sh NAME 41.Nm mksnap_ffs 42.Nd take a file system snapshot 43.Sh SYNOPSIS 44.Nm 45.Ar snapshot_name 46.Sh DESCRIPTION 47The 48.Nm 49utility creates a snapshot named 50.Ar snapshot_name . 51.Pp 52The group ownership of the file is set to 53.Dq Li operator ; 54the owner of the file remains 55.Dq Li root . 56The mode of the snapshot is set to be readable by the owner 57or members of the 58.Dq Li operator 59group. 60.Sh EXAMPLES 61Create a snapshot of 62.Pa /usr/home 63file system and mount the snapshot elsewhere: 64.Bd -literal -offset indent 65mksnap_ffs /usr/home/snapshot 66mdconfig -a -t vnode -o readonly -f /usr/home/snapshot 67mount -o ro /dev/md0 /mnt/ 68.Ed 69.Sh SEE ALSO 70.Xr chmod 2 , 71.Xr chown 8 , 72.Xr mdconfig 8 , 73.Xr mount 8 74.Sh HISTORY 75The 76.Nm 77utility first appeared in 78.Fx 5.1 . 79.Sh CAVEATS 80The disk full situation is not handled gracefully and may 81lead to a system panic when no free blocks are found. 82.Pp 83Every filesystem can have only up to 20 active snapshots. 84When this limit is reached, attempting to create more snapshots 85fails with 86.Er ENOSPC , 87and 88.Nm 89reports that it is 90.Dq out of space . 91