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. The table below describes partition table terminology.
Table 28-7 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.
The following partition table example is displayed from a 1.05-Gbyte disk using the format utility:
Total disk cylinders available: 2036 + 2 (reserved cylinders) Part Tag Flag Cylinders Size Blocks 0 root wm 0 - 300 148.15MB (301/0/0) 303408 1 swap wu 301 - 524 110.25MB (224/0/0) 225792 2 backup wm 0 - 2035 1002.09MB (2036/0/0) 2052288 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 usr wm 525 - 2035 743.70MB (1511/0/0) 1523088 7 unassigned wm 0 0 (0/0/0) 0 |
The partition table contains the following information:
Column Name |
Description |
---|---|
Part |
Partition (or slice number). See Table 28-7 for a description of this column. |
Tag |
Partition tag. See Table 28-7 for a description of this column. |
Flags |
Partition flag. See Table 28-7 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/c0t1d0s0 * /dev/rdsk/c0t1d0s0 partition map * * Dimensions: * 512 bytes/sector * 72 sectors/track * 14 tracks/cylinder * 1008 sectors/cylinder * 2038 cylinders * 2036 accessible cylinders * * Flags: * 1: unmountable * 10: read-only * * First Sector Last * Partition Tag Flags Sector Count Sector Mount Directory 0 2 00 0 303408 303407 / 1 3 01 303408 225792 529199 2 5 00 0 2052288 2052287 6 4 00 529200 1523088 2052287 /usr |
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 28-7 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 28-7 for a description of this column. |
Tag |
Partition tag. See Table 28-7 for a description of this column. |
Flags |
Partition flag. See Table 28-7 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. |