Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
PERIODIC-SNAPSHOT(8)	FreeBSD	System Manager's Manual	  PERIODIC-SNAPSHOT(8)

NAME
     periodic-snapshot -- run periodic UFS/ZFS backup snapshot maintenance
     task

SYNOPSIS
     periodic-snapshot

DESCRIPTION
     The periodic-snapshot utility is intended to be called by cron(8) to cre-
     ate and expire UFS/ZFS backup snapshots through the snapshot(8) command
     according to the snapshot_enable and snapshot_schedule settings from
     periodic.conf(5).

     The system	/etc/crontab will typically have entries for periodic-snapshot
     similar to	the following example:

	   # do	hourly/daily/weekly maintenance	of FreeBSD UFS/ZFS snapshots
	   0  *	 *  *  *  root	periodic-snapshot hourly
	   0  0	 *  *  *  root	periodic-snapshot daily
	   0  0	 *  *  0  root	periodic-snapshot weekly

     The /etc/defaults/periodic.conf system registry will typically contain
     the following defaults which keep periodic-snapshot disabled by default:

	   snapshot_enable="NO"
	   snapshot_schedule=""

     The snapshot_schedule variable values have	to conform to the following
     grammar:

	   <schedule>	 ::= <entry>*
	   <entry>	 ::= <fs> ("," <fs>)* ":" <spec>
	   <fs>		 ::= /^.*$/
	   <spec>	 ::= <gen_weekly> ":" <gen_daily> ":" <gen_hourly>
	   <gen_weekly>	 ::= <generation>
	   <gen_daily>	 ::= <generation>
	   <gen_hourly>	 ::= <generation> ("@" <hour> ("," <hour>)*)?
	   <generation>	 ::= /^[0-9]+$/
	   <hour>	 ::= /^(0?[0-9]|1[0-9]|2[0-3])$/

     The number	of all added "generation" numbers of a filesystem cannot be
     larger than 20 because this is the	maximum	number of snapshots which can
     be	created	on a UFS/ZFS filesystem. A "generation"	number of "0" disables
     the creation of backup snapshots.

     The used schedule heavily depends on how much generations of snapshots
     should be kept, which in turn depends on how much disk space is avail-
     able.

FILES
     /etc/crontab		  the periodic-snapshot	utility	is typically
				  called via entries in	the system default
				  cron(8) table.

     /etc/defaults/periodic.conf  system registry containing variables that
				  control the behaviour	of periodic-snapshot.

     /etc/periodic.conf		  this file contains local overrides for the
				  default periodic-snapshot configuration.

EXAMPLES
     In	order to configure UFS/ZFS backup snapshot creation, add lines to
     /etc/periodic.conf	similar	to:

	   snapshot_enable="YES"
	   snapshot_schedule="/,/usr:2:1:0 /var:0:2:4 /home:2:6:8@8,12,16,20"

     This schedules the	following UFS/ZFS backup snapshots: 2 weekly
     (weekly.[01]) and 1 daily (daily.0) generation of snapshots on the	/ and
     /usr filesystems, two daily (daily.[01]) and 4 hourly (hourly.[0123])
     generations of snapshots on the /var filesystem, and 2 weekly
     (weekly.[01]), 6 daily (daily.[0123456]) and 8 hourly (hourly.[01234567])
     generations of snapshots on the /home filesystem.	While the hourly snap-
     shots on /var are created every hour, the hourly snapshots	on /home are
     created on	08:00, 12:00, 16:00 and	20:00 only.

SEE ALSO
     sh(1), crontab(5),	periodic.conf(5), cron(8), snapshot(8),
     http://people.freebsd.org/~rse/snapshot/.

HISTORY
     The periodic-snapshot utility first appeared in FreeBSD.

AUTHORS
     Ralf S. Engelschall <rse@FreeBSD.org>

FreeBSD	13.0		      September	03, 2004		  FreeBSD 13.0

NAME | SYNOPSIS | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | HISTORY | AUTHORS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=periodic-snapshot&sektion=8&manpath=FreeBSD+13.1-RELEASE+and+Ports>

home | help