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dump(1M)							      dump(1M)

NAME    [Toc]    [Back]

     dump, rdump - incremental filesystem backup for EFS filesystems

SYNOPSIS    [Toc]    [Back]

     dump [ key	[ argument ... ] ] filesystem
     rdump [ key [ argument ...	] ] filesystem

DESCRIPTION    [Toc]    [Back]

     dump and rdump are	applicable only	to EFS filesystems, use	xfsdump(1m)
     for XFS filesystems.

     dump backs	up all files in	filesystem or files changed after a certain
     date to magnetic tape or files.  The key specifies	the date and other
     options about the dump.  key consists of characters from the set
     0123456789fusCcdbWwn.  Any	arguments supplied for specific	options	are
     given as subsequent words on the command line, in the same	order as that
     of	the options listed.

     If	no key is given, the key is assumed to be 9u and the filesystem
     specified is dumped to the	default	tape device /dev/tape.

     0-9  This number is the dump level.  All files modified since the last
	  date stored in the file /etc/dumpdates for the same filesystem at
	  lesser levels	are dumped.  If	no date	is determined by the level,
	  the beginning	of time	is assumed; thus the option 0 causes the
	  entire filesystem to be dumped.  For instance, if you	did a level 2
	  dump on Monday, followed by a	level 4	dump on	Tuesday, a subsequent
	  level	3 dump on Wednesday would contain all files modified or	added
	  to the filesystem since the level 2 (Monday) backup.	A level	0 dump
	  copies the entire filesystem to the dump volume.

     f	  Place	the dump on the	next argument file instead of the default tape
	  device /dev/tape. If the name	of the file is ``-'', dump writes to
	  standard output.  If the name	of the file is of the format
	  machine:device, the filesystem is dumped across the network to the
	  remote machine.  Since dump is normally run by root, the name	of the
	  local	machine	must appear in the .rhosts file	of the remote machine.
	  If the filename argument is of the form user@machine:device, dump
	  attempts to execute as the specified user on the remote machine.
	  The specified	user must have a .rhosts file on the remote machine
	  that allows root from	the local machine.  dump creates a remote
	  server, /etc/rmt, on the client machine to access the	tape device.

     u	  If the dump completes	successfully, write the	date of	the beginning
	  of the dump on file /etc/dumpdates.  This file records a separate
	  date for each	filesystem and each dump level.	 The format of
	  /etc/dumpdates is readable by	people,	consisting of one free format
	  record per line:  filesystem name, increment level, and ctime(3C)
	  format dump date.  /etc/dumpdates can	be edited to change any	of the
	  fields, if necessary.

									Page 1

dump(1M)							      dump(1M)

     s	  The size of the dump tape is specified in feet.  The number of feet
	  is taken from	the next argument. It is recommended that the C	option
	  be used instead, as it is more predictable.  When the	specified size
	  is reached, dump prompts the operator	and wait for the reel/volume
	  to be	changed.

     d	  The density of the tape, expressed in	BPI (bytes per inch), is taken
	  from the next	argument. This is used in calculating the amount of
	  tape used per	reel.  It is recommended that the C option be used
	  instead, as it is more predictable.

     b	  The blocking factor (number of 1-kilobyte blocks written out
	  together) is taken from the next argument. The default is 10.	 The
	  default blocking factor for tapes of density 6250 BPI	and greater is
	  32.  For some	network, tape type, and	server combinations, there may
	  be a significant throughput improvement by using a blocking factor
	  of 32, rather	than the default of 10,	when using rdump.  If values
	  larger than 32 are used, restore does	not correctly determine	the
	  block	size unless the	b option is also used.	To maximize tape
	  utilization, use a blocking factor that is a multiple	of 8.  For
	  most types of	supported tape drives, the greatest capacity and tape
	  throughput is	obtained using a blocking factor of 128	or even
	  larger; note that restore(1M)	automatically determines the blocking
	  factor only if it is 32 or less.

     C	  This specifies the total tape	capacity in 1-kilobyte blocks,
	  overriding the c, s, and d arguments if they are also	given.	Unlike
	  the size and density arguments, the capacity is used as specified,
	  no correction	factors	are applied.  Since capacity lost to retries
	  or underruns (by the drive), are not taken into account, you should
	  be conservative when specifying capacity.  The argument is parsed
	  with strtoul(3C), so it can be in any	base (for example, a 0x	prefix
	  specifies a hexadecimal value, a 0 prefix specifies octal, no	prefix
	  is decimal).	The argument can have a	k, K, m, or M suffix.  The
	  first	two multiply the value by 1024,	the third and fourth multiply
	  by 1048576, so a tape	with a 2.2 Gbyte capacity might	be specified
	  as C 2m allowing 10% loss to retries,	and so on.

	  When the specified capacity has been written,	dump prompts the
	  operator and wait for	the reel/volume	to be changed.	It is not
	  currently possible to	specify	different capacities for different
	  volumes of multi-volume backups.

     c	  Indicates that the tape is a cartridge tape instead of the standard
	  default half-inch reel.  This	should always be specified when	using
	  cartridge tapes, unless the C	option is used.	 The values for
	  blocking factor, size, and density are taken to be 10	(1-kilobyte
	  blocks), 5400	feet, and 1000 BPI respectively	unless overridden with
	  the b, s, or d option.

									Page 2

dump(1M)							      dump(1M)

     W	  dump tells the operator what filesystems need	to be dumped.  This
	  information is gleaned from the files	/etc/dumpdates and /etc/fstab.
	  The W	option causes dump to print out, for each filesystem in
	  /etc/dumpdates, the most recent dump date and	level and highlights
	  those	filesystems that should	be dumped.  The	mnt_freq field in the
	  /etc/fstab entry of the filesystem must be nonzero for dump to
	  determine whether the	filesystem should be dumped or not.  If	the W
	  option is set, no other option must be given and dump	exits

     w	  Is like W, but prints	only those filesystems that need to be dumped.

     n	  Whenever dump	requires operator attention, notify by means similar
	  to a wall(1) all of the operators in the group operator.

     dump reads	the character device associated	with the filesystem and	dumps
     the contents onto the specified tape device.  It searches /etc/fstab to
     find the associated character device.

NOTES    [Toc]    [Back]

     rdump is a	link to	dump.

   Operator Intervention    [Toc]    [Back]
     dump requires operator intervention on these conditions:  end of tape,
     end of dump, tape write error, tape open error, or	disk read error	(if
     there are more than a threshold of	32).  In addition to alerting all
     operators implied by the n	key, dump interacts with the operator on
     dump's control terminal at	times when dump	can no longer proceed or if
     something is grossly wrong.  All questions	dump poses must	be answered by
     typing yes	or no, appropriately.

     Since making a dump involves a lot	of time	and effort for full dumps,
     dump checkpoints itself at	the start of each tape volume.	If writing
     that volume fails for some	reason,	dump, with operator permission,
     restarts itself from the checkpoint after the old tape has	been rewound
     and removed and a new tape	has been mounted.

     dump reports periodically,	including usually the percentage of the	dump
     completed,	low estimates of the number of blocks to write in 1-kilobyte
     blocks (or, more strictly,	TP_BSIZE units from protocols/dumprestore.h),
     the number	of tapes it will take, the time	to completion, and the time to
     the tape change.  The estimated time is given as hours:minutes and	is
     based on the time taken to	dump the blocks	already	on tape.  It is	normal
     for this estimate to show variance, and the estimate improves over	time.
     The output	is verbose, so that others know	that the terminal controlling
     dump is busy and will be for some time.

   Suggested Dump Schedule    [Toc]    [Back]
     It	is vital to perform full level 0 dumps at regular intervals.  When
     performing	a full dump, bring the machine down to single-user mode	using
     shutdown -is.  Otherwise the dump may not be internally consistent	and
     may not restore correctly.	 While preparing for a full dump, it is	a good

									Page 3

dump(1M)							      dump(1M)

     idea to clean the tape drive and heads (most types	of drives require head
     cleaning for approximately	every 30 hours of tape motion).

     Incremental dumps allow for convenient backup and recovery	of active
     files on a	more frequent basis, with a minimum of media and time.
     However, there are	some trade-offs.  First, the interval between backups
     should be kept to a minimum (once a day at	least).	 To guard against data
     loss as a result of a media failure (a rare but possible occurrence), it
     is	a good idea to capture active files on (at least) two sets of dump
     volumes.  Keep unnecessary	duplication of files to	a minimum to save both
     operator time and media storage.  A third consideration is	the ease with
     which a particular	backed up version of a file can	be located and
     restored.	The following four-week	schedule offers	a reasonable trade-off
     between these goals.

	      Sun    Mon    Tue	   Wed	  Thu	 Fri
     Week 1:  Full   5	    5	   5	  5	 3
     Week 2:	     5	    5	   5	  5	 3
     Week 3:	     5	    5	   5	  5	 3
     Week 4:	     5	    5	   5	  5	 3

     Although the Tuesday through Friday incrementals contain extra copies of
     files from	Monday,	this scheme assures that any file modified during the
     week can be recovered from	the previous day's incremental dump.

   Dump	Parameters
     Since it is suggested that	the C option be	used instead of	the density
     and size options, and since those values are almost never really correct
     for any tape drive	except 9 track tapes, recommended values for these
     parameters	are no longer suggested	in this	man page.  As an example of
     the capacity, a typical QIC150 cartridge would use	C 140k,	a DDS1 90
     meter DAT or 112 meter 8mm	(8200 mode) cartridge would use	C 1800k, and a
     DDS2 120 meter cartridge would use	C 3800k.

EXAMPLES    [Toc]    [Back]

	  /dev/usr /usr	efs rw,raw=/dev/rdsk/dks0d1s6 0	0

     Here are a	few examples on	how to dump the	/usr filesystem	with the above
     /etc/fstab	entry.

	  dump 0Cfu 140k guest@kestrel:/dev/tape /usr

     does a level 0 dump of /usr onto a	remote cartridge tape device /dev/tape
     on	host kestrel using the guest account.  dump also updates the file

	  dump 2Cu 140k	/usr

     does a level 2 dump of /usr to the	local cartridge	tape device /dev/tape
     and also updates the file /etc/dumpdates.

									Page 4

dump(1M)							      dump(1M)

	  dump 0Cb 140k	128 /usr

     does a level '0' dump of /usr to the local	tape device /dev/tape using a
     blocking factor of	128.  The tape is specified to have a capacity of 140
     megabytes in the second, which allows for retries,	space lost to
     repositioning, and	so on.	It is also appropriate for a QIC 150 quarterinch
 tape drive.  The ordering of the arguments depends on	the ordering
     of	the key.

	  dump 1Cf 140k	/dev/mt/tps0d7 /usr
	  dump 1Cf 140k	/dev/mt/tps0d7 /dev/rdsk/dks0d1s6

     both do a level 1 dump of /usr to the local cartridge tape.

	  dump /usr

     does a level 9 dump of /usr to the	local tape device /dev/tape and
     updates the file /etc/dumpdates.

	  dump 9uCf 2048k /dev/mt/tps0d6nrnsv /os
	  dump 9uCf 2m /dev/mt/tps0d6nrnsv /os

     Both do a level 9 dump of /os to the local	tape device
     /dev/mt/tps0d6nrnsv where the tape	device being used is an	8mm tape
     drive, and	we are being somewhat optimistic about the capacity.

	  dump W

     prints out, for each filesystem in	/etc/dumpdates,	the most recent	dump
     date and level and	highlights those filesystems that should be dumped.

FILES    [Toc]    [Back]

     /dev/tape	      default tape unit	to dump	to
     /etc/dumpdates   new format dump date record
     /etc/fstab	      dump table: filesystems and frequency
     /etc/group	      to find group operator

SEE ALSO    [Toc]    [Back]

     restore(1M), rmt(1M), shutdown(1M), xfsdump(1M), xfsrestore(1M), wall(1),
     ctime(3C),	fstab(4), group(4), rhosts(4), dump(5),	mtio(7).

DIAGNOSTICS    [Toc]    [Back]

     While running, dump emits many verbose messages.

     The exit codes are

     0	Normal exit
     1	Startup	errors encountered
     3	Abnormal termination

									Page 5

dump(1M)							      dump(1M)

BUGS    [Toc]    [Back]

     Fewer than	32 read	errors on the filesystem are ignored.  Each reel
     requires a	new process, so	parent processes for reels already written
     just hang around until the	entire tape is written.

     dump with the W or	w options does not report filesystems that have	never
     been recorded in /etc/dumpdates, even if listed in	/etc/fstab.

     It	would be nice if dump knew about the dump sequence, kept track of the
     tapes scribbled on, told the operator which tape to mount when, and
     provided more assistance for the operator running restore.

     It	is recommended that incremental	dumps also be performed	with the
     system running in single-user mode.

     dump needs	accurate information regarding the length and density of the
     tapes used.  It can dump the filesystem on	multiple volumes, but since
     there is no way of	specifying different sizes for multiple	tapes, all
     tapes used	should be at least as long as the specified/default length.
     If	dump reaches the end of	the tape volume	unexpectedly (as a result of a
     longer than actual	length specification), it aborts the entire dump.
     This can be a problem when	writing	multiple dumps to the same physical
     tape, or when the tape drive supports hardware compression, and it	is not
     possible to determine the average compression ratio ahead of time.
     Currently the only	solution to this problem in this version of dump is to
     be	conservative in	specifying capacity.

									PPPPaaaaggggeeee 6666
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