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Backing up files means making copies of them, usually on removable media, as a safeguard in case the originals get lost or damaged. Backup tapes are convenient for restoring accidentally deleted files, but they are essential in case of serious hardware failures or other disasters.
Backing up files is one of the most crucial system administration functions. You must plan and carry out a procedure for regularly scheduled backups of your file systems for three major reasons:
When you back up file systems as scheduled, you have the assurance that you can restore anyone's files to a reasonably recent state. In addition, you may want to back up file systems to transport them from one system to another or to archive them saving files on a transportable media so that you can remove or alter the files that remain on the system.
When you plan a backup schedule, you need to consider:
Outlining possible backup strategies is beyond the scope of this book. See the ufsdump(1M) manual page for a suggested dump schedule. The discussions that follow describe how to use the ufsdump command to make backups and how to retrieve files using the ufsrestore command.
Table 4-7 lists the commands that you can use to back up and restore individual files and file systems.
|Back up and restore complete or individual file systems to a local or remote tape device||ufsdump and ufsrestore.|
|Back up complete file systems for all systems on a network from a server||Solstice Backup software. Refer to the Solstice Backup 4.2 User Guide.|
|Back up and restore an NIS+ master server||nisbackup and nisrestore. Refer to the nisbackup and nisrestore manual pages.|
The ufsdump command uses a set of defaults when you do not specify any tape characteristics. You can specify tape cartridge (-c), density (-d), size (-s), and number of tracks (-t). Note that you can specify the options in any order as long as the arguments that follow match the order of the options. See Tape Capacity Arguments to the ufsdump Command provides some arguments to the ufsdump command that work well for different types of tape cartridges.
|Diskette||ufsdump Ds 1422|
|60-Mbyte cartridge||ufsdump cdst 1000 425 9|
|150-Mbyte cartridge||ufsdump cdst 1000 700 18|
|1/2-inch tape||ufsdump dsb 1600 2300 126|
|2.3-Gbyte 8-mm tape||ufsdump dsb 54000 13000 126|
|5.0-Gbyte 8-mm tape||ufsdump dsb 54000 13000 126|
|5.0-Gbyte 4-mm tape||ufsdump b 96|
To do a full backup on a file system, all users must be logged out and you must bring the system to single-user mode. (See "Tape Device Naming Conventions" in Chapter 3 if you need information about tape device names.)
You can dump or restore files from a remote drive by adding remote-host: to the front of the tape device name. Here is the syntax:
For example, the device name for a remote tape drive /dev/rmt/0, on the system oak, would be oak: /dev/rmt/0.
Follow these steps to do a level 0 (full) backup of a file system:
oak% su Password: # init s # ufsdump Øcuf /dev/rmt/Ø cØtØdØs7 DUMP: Date of this level Ø dump: Wed Mar 11 1Ø:16:53 1992 DUMP: Date of last level Ø dump: the epoch DUMP: Dumping /dev/rdsk/cØt3dØs7 (/export/home) to /dev/rmt/Ø DUMP: mapping (Pass I) [regular files] DUMP: mapping (Pass II) [directories] DUMP: estimated 956 blocks (478KB) DUMP: Writing 63 Kilobyte records DUMP: dumping (Pass III) [directories] DUMP: dumping (Pass IV) [regular files] DUMP: level Ø dump on Wed Mar 11 1Ø:16:53 1992 DUMP: 956 blocks (478KB) on 1 volume DUMP: DUMP IS DONE #
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