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|System Administration Guide: Devices and File Systems Oracle Solaris 10 1/13 Information Library|
The following information is described in this section:
The format utility is most often used by system administrators to partition a disk. The steps are as follows:
Determine which slices are needed.
Determine the size of each slice or partition.
Use the format utility to partition the disk.
Label the disk with new partition information.
Create the file system for each partition.
The easiest way to partition a disk is to use the modify command from the partition menu of the format utility. The modify command enables you to create partitions by specifying the size of each partition, without having to keep track of the starting cylinder boundaries. The modify command also keeps tracks of any disk space that remains in the “free hog” slice.
An important part of the disk label is the partition table. The partition table identifies a disk's slices, the slice boundaries (in cylinders), and the total size of the slices. You can display a disk's partition table by using the format utility. The following table describes partition table terminology.
Table 7-3 Partition Table Terminology
Partition flags and tags are assigned by convention and require no maintenance.
For more information about displaying the partition table, see the following references:
The following format utility output shows an example of a partition table from a 74-GB disk with a VTOC label displayed:
Total disk cylinders available: 38756 + 2 (reserved cylinders) Part Tag Flag Cylinders Size Blocks 0 root wm 3 - 2083 4.00GB (2081/0/0) 8390592 1 swap wu 2084 - 3124 2.00GB (1041/0/0) 4197312 2 backup wm 0 - 38755 74.51GB (38756/0/0) 156264192 3 unassigned wm 0 0 (0/0/0) 0 4 unassigned wm 0 0 (0/0/0) 0 5 unassigned wm 0 0 (0/0/0) 0 6 unassigned wm 0 0 (0/0/0) 0 7 home wm 3125 - 38755 68.50GB (35631/0/0) 143664192 8 boot wu 0 - 0 1.97MB (1/0/0) 4032 9 alternates wu 1 - 2 3.94MB (2/0/0) 8064 partition>
The partition table that is displayed by the format utility contains the following information.
The following is an example of an EFI disk label displayed by using the prtvtoc command.
# prtvtoc /dev/rdsk/c4t1d0s0 * /dev/rdsk/c4t1d0s0 partition map * * Dimensions: * 512 bytes/sector * 2576941056 sectors * 2576940989 accessible sectors * * Flags: * 1: unmountable * 10: read-only * * First Sector Last * Partition Tag Flags Sector Count Sector Mount Directory 0 2 00 34 629145600 629145633 1 4 00 629145634 629145600 1258291233 6 4 00 1258291234 1318633404 2576924637 8 11 00 2576924638 16384 2576941021
The output of the prtvtoc command provides information in the following three sections:
This temporary slice donates, or “frees,” space when you expand a slice, and receives, or “hogs,” the discarded space when you shrink a slice. For this reason, the donor slice is sometimes called the free hog.
The free hog slice exists only during installation or when you run the format utility. There is no permanent free hog slice during day-to-day operations.
For information on using the free hog slice, see SPARC: How to Create a Disk Slice for a ZFS Root File System or x86: How to Create a Disk Slice for a ZFS Root File System.