Copyright (c) 2003 The NetBSD Foundation, Inc.
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This code is derived from software contributed to The NetBSD Foundation
by Juergen Hannken-Illjes.
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.Dd December 10, 2003 .Dt FSSCONFIG 8 .Os .Sh NAME .Nm fssconfig .Nd configure file system snapshot devices .Sh SYNOPSIS .Nm .Op Fl cx .Ar device .Ar path .Ar backup .Op Ar cluster Op Ar size .Nm .Fl u .Ar device .Nm .Fl l Op Fl v .Op Ar device .Sh DESCRIPTION The .Nm command configures file system snapshot pseudo disk devices. It will associate the file system snapshot disk .Ar device with a snapshot of .Ar path allowing the latter to be accessed as though it were a disk. Data written through the .Ar path will be saved in .Ar backup which must not reside on the snapshotted file system. If .Ar backup is a regular file, it will be created with length .Ar size . Default size is 10% the size of .Ar path . Data is saved to .Ar backup in units of .Ar cluster bytes.
p Options indicate an action to be performed: l -tag -width indent t Fl c Configures the device. If successful, references to .Ar device will access the contents of .Ar path at the time the snapshot was taken. If .Ar backup is a directory a temporary file will be created in this directory. This file will be unlinked on exit. t Fl l List the snapshot devices and indicate which ones are in use. If a specific .Ar device is given, then only that will be described. t Fl u Unconfigures the .Ar device . t Fl v Be more verbose listing the snapshot devices. t Fl x Unlink .Ar backup after the .Ar device is configured. .El
p If no action option is given, .Fl c is assumed. .Sh FILES l -tag -width /etc/disktab -compact t Pa /dev/rfss? t Pa /dev/fss? .El .Sh EXAMPLES .Dl fssconfig fss0 /usr /tmp/back
p Configures the snapshot device
a fss0 for a snapshot of the
a /usr file system. Data written through
a /usr will be backed up in
p .Dl fssconfig fss1 / /dev/rsd0e 8192
p Configures the snapshot device
a fss1 for a snapshot of the
a / file system. Data written through
a / will be backed up in
a /dev/rsd0e . The backup will take place in units of 8192 bytes.
p .Dl fssconfig -u fss0
p Unconfigures the
a fss0 device. .Sh SEE ALSO .Xr opendisk 3 , .Xr fss 4 , .Xr mount 8 , .Xr umount 8 .Sh HISTORY The .Nm command appeared in .Nx 2.0 . .Sh BUGS The .Xr fss 4 driver is .Em experimental . Be sure you have a backup before you use it.
Indexes created Tue Oct 28 12:10:06 GMT 2025