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PDUMPFS(8)		FreeBSD	System Manager's Manual		    PDUMPFS(8)

     pdumpfs --	A daily	backup system similar to Plan9's dumpfs

     pdumpfs src-dir dest-dir [dest-basename]

     pdumpfs is	a simple daily backup system written in	Ruby (ruby(1)),	which
     is	similar	to Plan9's dumpfs that preserves every daily snapshot.

     Back up your home directory with pdumpfs, and you can retrieve any	past
     day's snapshot of any file.

     pdumpfs constructs	each day's snapshot in the directory named YYYY/MM/DD
     under the destination directory.  All source files	are copied to the
     snapshot directory	for the	first time, and	on and after the second	time,
     pdumpfs copies only updated or newly created files	and stores unchanged
     files as hard links to the	files of the previous day's snapshot to	save
     disk space.

     The latest	version	of pdumpfs is always available at

     To	backup your home directory /home/yourname to /backup, run the follow-
     ing command.

	   pdumpfs /home/yourname /backup >/backup/log 2>/backup/error-log

     On	and after the second day, it is	a good idea to invoke the backup com-
     mand with cron(8) daemon.	Adding the following line to your crontab file
     allows you	to back	up your	home directory at 5 a.m. everyday.

	   00 05 * * * pdumpfs /home/yourname /backup >/backup/log

     If	the backup system works	well, you can retrieve any given day's file
     with a file name like /backup/2001/02/19/yourname/...

     -	 pdumpfs can only handle normal	files, directories, and	symbolic

     -	 pdumpfs may not work on systems other than UNIX because pdumpfs uti-
	 lizes hard links.

     -	 pdumpfs is not	suited for a directory containing large	files which
	 are updated frequently.

     -	 If more than 31 day absence occurs, incremental backup	would not be
	 performed.  So, back up your files on a daily basis.

     -	 With pdumpfs, you can safely remove unnecessary files because the
	 past files can	be retrieved at	any time.  However, you	must not rely
	 too much on pdumpfs.  It may have serious bugs.

     -	 If the	total disk usage increases by 10 MB everyday, about 4 GB disk
	 space will be consumed	every year.  It	would not matter so much con-
	 sidering the recent evolution of computer resources.

     -	 Back up your files to a physically separated device.

     -	 On some systems, files	can be made immutable.

	 To make all files in /backup immutable	on Linux, run the following
	 command as root:

	       chattr -R +i /backup

	 On 4.4BSD derived systems, run	the following command as root:

	       chflags -R schg /backup

	 These commands	will keep you from accidentally	removing your backup
	 files with rm -rf.

     pdumpfs and the HTML document were	written	by Satoru Takabayashi

     This manual page was translated from the HTML document by Hiroyuki
     Shimada <>, and reformatted by Akinori MUSHA

     chattr(1),	chflags(1), crontab(5),	cron(8)

			       November	25, 2001


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