Sun Certified System Administrator for Solaris 10 Study Guide Exams 310-XXX & 310-XXX

As a system administrator, you will be performing regularly scheduled backups as a protection against data loss. If you want to make sure that all the files in the system are backed up correctly, use the ufsdump command after unmounting the file system or after putting the Solaris system into single-user mode. The ufsdump command has a built-in capability for full and incremental backups. The ufsdump command creates the /etc/dumpdates file, which it uses to store and retrieve information to coordinate incremental backups on top of a full backup.

You cannot use the ufsdump command to back up an active file system—that is, a file system that is mounted and is in multiuser mode. However, if you do want to make a backup of an active file system, you can take a snapshot of the file system by using the fssnap command and then back up the snapshot by using an appropriate backup command, such as ufsdump, tar, or cpio. There are other backup commands available to meet varying needs. For example, you can use the cpio command to copy a file system from one disk to another, the dd command to clone an entire disk, and the tar command to package files (or directory subtrees) and transport them across UNIX systems.

You can use the ufsrestore command to restore an individual file or a complete file system from removable media to a directory. If you want to choose the files and directories from the backup file system that you want to restore, it's better to use the command interactively by specifying the -i option. If you are restoring the entire file system and it was backed up by using incremental backups, you will need to understand the basic concept of incremental backups and how they are represented by dump levels. You can restore the backup file system from a UFS snapshot the way you would restore any other backup.

Inside the Exam

Comprehend

• To make sure the entire data is backed up, you should put the system into a single-user mode or unmount the file system before backing up a file system by using the ufsdump command.

• The fssnap command does not back up the file system to an external device; it creates a snapshot on the disk.

• When you use the fssnap command with the unlink option, the backing-store file will not be visible to you, but it will be automatically deleted when, the snapshot is deleted.

Look Out

• The destination for the backing-store files in the fssnap command must be on a file system different from the file system that is being captured in the snapshot.

• There are two ways of deleting a UFS snapshot: reboot the system or use the fssnap -d command.

• Do not use the /tmp directory as a temporary location for restoring a UFS file system, because /tmp is not usually mounted as a UFS file system.

Memorize

• The ufsdump command can be used only on unmounted or read-only mounted file systems. If you want to take the snapshot of an active file system, use the fssnap command, instead.

• The restoresymtable file is created and used by the ufsrestore utility to checkpoint the restoration. The /etc/dumpdates file is created by the ufsdump command, and backing-store file is created by the fssnap command.

• The ufsrestore command used with the -x option overwrites the existing files.

• Typical use of backup commands: cpio to copy a file system from one disk to another, dd to clone an entire disk, tar to package files (or directory subtrees) and transport them across UNIX systems, and ufsdump to perform full and incremental backups.