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btextract(8)							 btextract(8)


  btextract - Extracts the file	systems	from tape in single-user mode in




  The btextract	command	is a shell script that restores	file systems from
  tapes	that contain the bootable Standalone System (SAS) kernel.  The SAS
  kernel is created using the btcreate utility.	 You can perform a default
  restore or an	advanced restore operation.

  Use the default restore option when you want to duplicate the	customized
  system on more than one machine of the same hardware platform	type.  When
  you perform a	default	restore, you cannot specify which disk partitions to
  use. Instead,	the btextract command restores file systems using the disk
  partition information	gathered during	the btcreate session. The restore
  operation overwrites all existing information	on the target drive.


       To perform a default restore operation, the disk	configuration of the
       system you backed up must be the	same as	the system you are restoring.
       Use the diskconfig GUI or the disklabel and newfs commands to prepare
       a disk to receive the extracted tape contents.

  During an advanced restore operation,	the btextract command prompts you to
  enter	the name of a disk partition. The file systems are restored to the
  specified partition.


       During an advanced restore operation, the btextract command assigns
       the b partition of the root disk	as the swap partition.

  You cannot restore a file system that	is more	than 100% full to a partition
  of the same size as the original partition. During the restore of the	UFS
  file system, the /sbin/restore command adds a	new file named restoresymt-
  able.	The presence of	this restoresymtable file can make the restored	file
  system larger	than the source	partition size listed in the output from the
  /sbin/disklabel command.

  For example, on the source system, the disklabel shows the target h parti-
  tion to be:

       h:    86758  1212416    4.2BSD

  The UFS file system is as follows:

       Filesystem  512-blocks	    Used   Available Capacity  Mounted on
       /dev/dsk8h	83812	   83786	   0   112%    /bootable

  The file system is 112% full.	This file system cannot	be restored on the
  target file system of	86758 blocks (512-byte blocks),	because	the following
  file is created by the /sbin/restore command.

       -rw-r--r--   1 root   system   27368 Jul	 2 09:33 restoresymtable

  The /sbin/restore command creates a restoresymtable file that	exceeds	the
  112% range.  The solution is to use a	partition of about 86996 (512-byte
  blocks), about 3.8% larger than the actual file size.

  Using	btextract

  To use the btextract utility,	place the system in a halt state, initialize
  the system, then boot	from the tape as follows:

       >>>>>> init
       >>>>>> show	dev
       >>>>>> boot	-fl "nc" MKA500

  In the preceding example, the	show dev command provides the device name
  under	BOOTDEV, and MKA500 is the BOOTDEV.

  After	the initial boot is complete, the shell	invokes	the btextract com-
  mand.	If you created a /usr/lib/sabt/sbin/custom_install.sh script during
  the btcreate session,	the btextract command invokes the custom_install.sh
  script before	exiting. See btcreate for more information.

  You can optionally label disks using your own	disklabel script.   If a cus-
  tomized disk labeling	script is not present, the btextract command labels
  the disks in the usual manner.   A customized	disklabel script has the fol-
  lowing restrictions:

    +  It must be located in the /usr/lib/sabt/etc directory.

    +  It must be named	custom_disklabel_file.

  After	the btextract command completes, you must shut down the	system,	then
  reboot the system from the restored disk as follows:

       # shutdown -h now
       >>>>>> boot	DKA100

  In the preceding example, DKA100 is the BOOTDEV.

  Creating a Custom Prerestore File

  When you boot	a system using bootable	tape, the btextract command prompts
  you to create	an answer file that provides the minimum information needed
  to complete the boot and restore operation. This custom_prerestore file is
  a text file located in the /usr/lib/sabt/etc directory. The minimum con-
  tents	are as follows:

       TAPE_USED="/dev/tape/tape0_d1"  #Tape drive used
       RESTORE_TYPE="no"	       #Restore	type yes=DEFAULT no=ADVANCED
       SPART="b"		       #Primary	Swap drive partition

  You can also create the custom_prerestore file manually, and use it to
  fully	automate the recovery procedure. The file can contain the following

    +  INTERACTIVE=["yes | no"]	- Specifies whether the	session	is to be
       interactive or not. A yes entry forces an interactive session. A	typi-
       cal entry is as follows:

    +  TAPE_USED="device_special_file" - Specifies the device special file
       name of the tape	drive from which the standalone	kernel was booted. A
       typical entry is	as follows:

    +  RESTORE_TYPE=["yes | no"] - Specifies whether this is to	be a default
       (yes) or	an advanced restore (no). A typical entry is as	follows:

    +  SDRIVE="disk_type device	name" -	Specifies the primary swap disk
       drive. This entry requires the following	parameters:

	 -- disk_type -	The disk device	model, such as HB00931B93 . You	can
	    obtain this	information by using the following command:
		 # hwmgr -show component | grep	iomap

	    The	hardware identifier is shown under the HWID column in the
	    command output. You	use this information to	determine the device
	    name of a disk.

	 -- device name	- The device instance, such as dsk8. This information
	    is part of the device special file name assigned to	the disk. You
	    can	obtain this information	by using the following command:
		 # hwmgr -show scsi
		  32:  0	cymro	  disk	  none	  2	 1    dsk0   [0/0/0]

	    In the preceding command output, the entry under the HWID column
	    identifies the disk	that you chose by using	the show component
	    option. The	HWID is	32 in this example.

       A typical entry is as follows:
	    SDRIVE="HB00931B93 dsk13"

    +  SPART="partition_id" - Specifies	the primary swap partition on the
       restored	disk.  A typical entry is as follows:

    +  DDRIVE_1="disk_type device name"	- Specifies the	root file system disk
       drive. A	typical	entry is as follows:
	    DDRIVE_1="RZ1CB-CS dsk13"

    +  PPART_1="partition_id" -	Specifies the root file	system partition. A
       typical entry is	as follows:

    +  DDRIVE_2="disk_type device name"	- Specifies the	disk drive used	for
       the /usr	file system. A typical entry is	as follows:
	    DDRIVE_2="HB00931B93 dsk11"

    +  PPART_1="partition_id" -	Specifies the /usr file	system partition.  A
       typical entry is	as follows:

    +  DDRIVE_N="disk_type device name"	Specifies the disks used for each
       additional file system that is restored,	where N	is an integer ranging
       from 3 to the total number of file systems to be	restored. Use entries
       similar to the following:
	    DDRIVE_3="HB00931B93 dsk12"

    +  PPART_N="partition_id " Specifies the partitions	used for each addi-
       tional file system that is restored, where N is an integer ranging
       from 3 to the total number of filesystems to be restored. Use entries
       similar to the following:

  To insert comments in	the custom prerestore file, preceded each comment
  line with the	number symbol (#).


  0 (zero)

  >>0  An error occurred.


      Log of the btextract process in memory

      Copy of the btextract process on the restored root file system

      Script used to customize the restored image

      A	custom disklabel file read by btextract


  Commands:  addvol(8),	btcreate(8), df(1), disklabel(8), lmf(8), mkfdmn(8),
  mkfset(8), newfs(8), restore(8), sh(1), vrestore(8)