System Administration Guide, Volume I

Partition Table

An important part of the disk label is the partition table which identifies a disk's slices, the slice boundaries (in cylinders), and total size of the slices. A disk's partition table can be displayed using the format utility. Table 21-7 describes partition table terminology.

Table 21-7 Partition Table Terminology


Partition Term	Value	Description
Number	0-7	Partition or (slice number). Valid numbers are 0-7.
Tag	0=UNASSIGNED 1=BOOT 2=ROOT 3=SWAP 4=USR 5=BACKUP 7=VAR 8=HOME	A numeric value that usually describes the file system mounted on this partition.
Flags
	wm	The partition is writable and mountable.
	wu rm	The partition is writable and unmountable. This is the default state of partitions dedicated for swap areas. However, the `mount` command does not check the "not mountable" flag.
	rm	The partition is read only and mountable.

Partition flags and tags are assigned by convention and require no maintenance.

See "How to Display Disk Slice Information" or "How to Examine a Disk Label" for more information on displaying the partition table.

Examples--Partition Tables

The following partition table example is displayed from a 535-Mbyte disk using the format utility:

The partition table contains the following information:

Column Name	Description
`Part`	Partition (or slice number). See Table 21-7 for a description of this column.
`Tag`	Partition tag. See Table 21-7 for a description of this column.
`Flags`	Partition flag. See Table 21-7 for a description of this column.
`Cylinders`	The starting and ending cylinder number for the slice.
`Size`	The slice size in Mbytes.
`Blocks`	The total number of cylinders and the total number of sectors per slice in the far right column.

The following example displays a disk label using the prtvtoc command.

# prtvtoc /dev/rdsk/c0t3d0s0
* /dev/rdsk/c0t3d0s0 partition map
*
* Dimensions:
*     512 bytes/sector
*      80 sectors/track
*       9 tracks/cylinder
*     720 sectors/cylinder
*    2500 cylinders
*    1151 accessible cylinders
*
* Flags:
*   1: unmountable
*  10: read-only
*
*                     First   Sector   Last
* Partition Tag Flags Sector  Count   Sector  Mount Directory
       0     2   00        0   66240   66239   /
       1     3   01    66240  131760  197999
       2     5   00        0  828720  828719
       3     0   00   198000   66240  264239   /export
       4     0   00   264240   66240  330479   /export/swap
       5     0   00   330480   72000  402479   /opt
       6     4   00   402480  385200  787679   /usr
       7     8   00   787680   41040  828719   /export/home
#

The disk label includes the following information:

Dimensions - This section describes the physical dimensions of the disk drive.

Flags - This section describes the flags listed in the partition table section. See Table 21-7 for a description of partition flags.

Partition (or Slice) Table - This section contains the following information:

Column Name	Description
`Partion`	Partition (or slice number). See Table 21-7 for a description of this column.
`Tag`	Partition tag. See Table 21-7 for a description of this column.
`Flags`	Partition flag. See Table 21-7 for a description of this column.
First Sector	The first sector of the slice.
Sector Count	The total number of sectors in the slice.
`Last Sector`	The last sector number in the slice.
`Mount Directory`	The last mount point directory for the file system.