Backups Under Solaris

Other Backup Utilities

In addition the basic Unix backup utilities, Solaris offers ufsdump and ufsrestore. These two commands function as a pair. ufsrestore can only restore from tapes created by ufsdump. Both are called from the command line and follow the syntax:

ufsdump options arguments filenames

ufsrestore options argument filenames

ufsdump only copies data from a raw disk slice. It does not copy free blocks. If a directory contains a symbolic link that points to a file on another disk slice, the link itself is copied. When ufsdump is used with the u option, the /etc/dumpdates file is updated. This file keeps a record of when filesystems were last backed up, including the level of the last backup, day, date and time. ufsdump can be used to back up individual files and directories as well as entire filesystems.

If ufsdump is run without options or arguments the following defaults are assumed:

ufsdump 9uf /dev/rmt/0 filenames

This means that ufsdump will create a level 9 incremental of the specified file, update /etc/dumpdates, and dump the files to /dev/rmt/0.

ufsdump also supports an S option to estimate the amount of space, in bytes, that the backup will require before actually creating it. This number can then be divided by the capacity of the tape to determine how many tapes the backup will need.

A series of tape characteristics and options can also be specified.

• c=cartridge
• d=density
• s=size
• t=number of tracks

ufsdump cdst 1000 425 9

This specifies a cartridge tape with a density of 1000, 425MB, and nine tracks. In terms of tape options the syntax is as follows:

ufsdump 9uf /dev/rmtXAbn filenames

Where

• X=the number of the drive beginning with 0.
• A=optional density.
  • l=low
  • m=medium
  • h=high
  • u=ultra
  • c=compressed
• b=specifies Berkeley SunOS 4.X compatibility.
• n=no rewind option, which allows other files to be appended to the tape.

ufsrestore has an interactive mode which can be used to select individual files and directories for restoration. It also supports an option to read the table of contents from the archive file instead of the backup media.

Limits of ufsdump:

• It does not automatically calculate the number of tapes needed to backup a filesystem.
• It does not have a built in error checking mechanism.
• It does not enable the backing up of files that are remotely mounted from a server.

Solaris also supplies volcopy, a utility to make an image or literal copy of a file system.

Tips and Quirks

The Solaris version of tar includes extra options. The -I option allows a list of files and directories that are backed up to be put into a text file. The -X option allows an exclusion file to be specified that lists the names of files and directories that should be skipped.

The Solaris version of mt supports an asf subcommand which moves the tape to the nth file. n being the number of the file.