Preparing for File System Backups

The preparation for backing up file systems begins with planning, which is described in Chapter 24, Backing Up and Restoring File Systems (Overview) and includes choosing the following:

• The file systems to back up

• The type of backup (full or incremental) to perform

• A backup schedule

• A tape drive

For more information, see Chapter 24, Backing Up and Restoring File Systems (Overview).

This section describes two other tasks you might need to perform before you back up file systems:

• Finding the names of file systems to back up

• Determining the number of tapes that are needed for a full backup

How to Find File System Names

1. Display the contents of the /etc/vfstab file.

   $ more /etc/vfstab

2. Look in the mount point column for the name of the file system.
3. Use the directory name listed in the mount point column when you back up the file system.

Example 25-1 Finding File System Names

In this example, the file systems to be backed up are root (/), /usr, /datab, and /export/home.

$ more /etc/vfstab
#device           device               mount        FS    fsck mount   mount
#to mount         to fsck              point        type  pass at boot options
/devices           -                   /devices     devfs   -     no      -
.
.
.
/proc              -                    /proc       proc    -     no      -
/dev/dsk/c0t0d0s1  -                    -           swap    -     no      -
/dev/dsk/c0t0d0s0 /dev/rdsk/c0t0d0s0   /            ufs     1     no      -
/dev/dsk/c0t0d0s6 /dev/rdsk/c0t0d0s6   /usr         ufs     1     no      -
/dev/dsk/c0t0d0s5 /dev/rdsk/c0t0d0s5   /datab       ufs     2     yes     -
/dev/dsk/c0t0d0s7 /dev/rdsk/c0t0d0s7   /export/home ufs     2     yes     -
swap              -                    /tmp         tmpfs   -     yes     -

How to Determine the Number of Tapes Needed for a Full Backup

1. Become superuser or assume an equivalent role.
2. Estimate the size of the backup in bytes.

   # ufsdump [0]S file-system

   Use the S option to display the estimated number of bytes that are needed to do the backup if this is the first backup of the file system.

   Use the 0S option to display the estimated number of bytes that are needed to do the backup if this is not the first backup of the file system.

3. Divide the estimated size by the capacity of the tape to determine how many tapes you need.

   For a list of tape capacities, see Table 24-5.

Example 25-2 Determining the Number of Tapes

In this example, the file system of 489,472 bytes easily fits on a 150-Mbyte tape.

# ufsdump S /export/home
489472