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btextract(8)
NAME
btextract - Extracts the file systems from tape in single-user mode in
memory
SYNOPSIS
/usr/sys/bin/btextract
DESCRIPTION
The btextract utility 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.
A DEFAULT restore is used by system administrators who 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 for the restore operation. Instead, the
btextract utility restores file systems using the disk partition
information gathered during the btcreate session; all existing information
is overwritten.
Note
To perform a DEFAULT restore, the disk configuration of the system you
backed up must be the same as the system you are restoring.
During an ADVANCED restore, you are prompted to enter the name of the disk
partition where the file systems are to be restored.
Note
During an ADVANCED restore, the btextract utility assigns the b
partition of the root disk as the swap partition.
A file system which is more than 100% full cannot be restored in 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
restoresymtable. The presence of this restoresymtable file can make the
restored file system larger than the source partition size listed in the
/sbin/disklabel output.
For example, on the source system, the disklabel shows the target h
partition to be:
h: 86758 1212416 4.2BSD
And 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 (512-blocks), as the following file is created
by the /sbin/restore command.
-rw-r--r-- 1 root system 27368 Jul 2 09:33 restoresymtable
The command /sbin/restore creates a restoresymtable file that exceeds the
112% range. The solution is to use a partition of about 86996 (512-
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 previous example, the show dev command provides the device name
under BOOTDEV and MKA500 is the BOOTDEV.
Once the initial boot is complete, the shell invokes the btextract utility.
If you created a /usr/lib/sabt/sbin/custom_install.sh script during the
btcreate session, the btextract utility invokes the custom_install.sh
script before exiting. See the btcreate reference page for more
information.
You also have the option to label disks using your own disklabel script.
If a customized disklabel script is not present, the btextract command will
label the disks in the usual manner. A customized disklabel script has
the following restrictions:
· It must be located in the /usr/lib/sabt/etc directory.
· It must be named custom_disklabel_file.
After the btextract utility completes, you must shut down the system, then
reboot the system from the restored disk as follows:
# shutdown -h now
>>> boot DKA100
In the previous example, DKA100 is the BOOTDEV.
RETURN VALUES
0 (Zero)
Success.
>0 An error occurred.
FILES
/var/adm/btextract.log
Log of the btextract process in memory
/btextract.log
Copy of the btextract process on the restored root file system
/usr/lib/sabt/sbin/custom_install.sh
Script used to customize the restored image
/usr/lib/sabt/etc/custom_disklabel_file
A custom disklabel file read by btextract
SEE ALSO
Commands: addvol(8), btcreate(8), df(1), disklabel(8), lmf(8), mkfdmn(8),
mkfset(8), newfs(8), restore(8), sh(1), vrestore(8)
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Index for
Section 8 |
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Alphabetical
listing for B |
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Top of
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