Displaying a Disk's Partitions With prtvtoc

Displaying a Disk's Partitions With prtvtoc

Use the prtvtoc command to get information about the size and partitions of a disk. Only the superuser can use this command. The command is:

prtvtoc device

device is optional; when it is omitted, prtvtoc displays information for the system disk. device is the raw device name (see the section "Device Names" in Chapter 1) of the disk volume header. The /dev/rdsk portion of the device name can be omitted if desired. For example, for a SCSI disk that is drive address 1 on controller 0, device is dks0d1vh. (See the section "Device Names" in Chapter 1 for more information on device names.)

An example of the output of prtvtoc is:

Printing label for root disk

* /dev/rdsk/dks0d1vh (bootfile "/unix")
*     512 bytes/sector
*      85 sectors/track
*       9 tracks/cylinder
*       3 spare blocks/cylinder
*    2726 cylinders
*       4 cylinders occupied by header
*    2722 accessible cylinders
*
* No space unallocated to partitions

Partition  Type  Fs   Start: sec   (cyl)    Size: sec    (cyl)  Mount Directory
 0          efs  yes        3048  (   4)        51054   (  67)   /
 1          raw            54102  (  71)        81534   ( 107) 
 6          efs  yes      135636  ( 178)      1941576   (2548)   /usr
 8       volhdr                0  (   0)         3048   (   4) 
10       volume                0  (   0)      2077212   (2726)

The first section of the output shows the device parameters that can be used to figure out the capacity of the disk (remember that 1 kilobyte = 1024 bytes and 1 megabyte = 1048576 bytes):

512 bytes/block * 85 blocks/track * 9 tracks/cylinder * 2722 cylinders: = 1,066,152,960 bytes
= 1,041,165 kilobytes
= 1,016 megabytes

The partition table at the end of the output lists the partitions, their type (name or filesystem type), whether they contain a filesystem, their location on the disk (start and size in blocks and cylinders), and mount directory for filesystems. The partitions in this output are shown graphically in Figure 1-4.

Another example of the output of prtvtoc, showing fractional numbers of cylinders per partition, is:

# prtvtoc /dev/rdsk/dks0d2vh
* /dev/rdsk/dks0d2vh (bootfile "/unix")
*     512 bytes/sector
*     115 sectors/track
*      20 tracks/cylinder
*      20 spare blocks/cylinder
*    3865 cylinders
*       2 cylinders occupied by header
*    3863 accessible cylinders
*
* No space unallocated to partitions
Partition  Type  Fs   Start: sec   (cyl)    Size: sec    (cyl)  Mount
Directory
   0          xfs  yes        4560  (   2)      8684310  (3808.9)  /usr/people
   1          raw          8688870 (3810.9)      125000  (  54.8)
   8       volhdr                0  (   0)         4560   (   2) 
  10       volume                0  (   0)      8813870  (3865.7)