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System Administration Guide: Devices and File Systems

Chapter 10 Managing Disks (Overview)

This chapter provides overview information about Oracle Solaris disk slices and introduces the format utility.

This is a list of overview information in this chapter.

For instructions on how to add a disk to your system, see Chapter 12, SPARC: Adding a Disk (Tasks) or Chapter 13, x86: Adding a Disk (Tasks).

What's New in Disk Management?

This section describes new disk management features in the Solaris release.

For a complete listing of new Solaris features and a description of Solaris releases, see Oracle Solaris 10 9/10 What’s New.

Two-Terabyte Disk Support for Installing and Booting the Solaris OS

Solaris 10 10/09: In previous Solaris releases, you could not install and boot the Solaris OS from a disk that was greater than 1 TB in size. In this Solaris release, you can install and boot the Solaris OS from a disk that is up to 2 TB in size. In previous releases, you also had to use an EFI label for a disk that is larger than 1 TB. In this release, you can use the VTOC label on any size disk, but the addressable space by the VTOC is limited to 2 TB.

The Solaris disk drivers and disk utilities have been updated to provide the following support:

Keep in mind that you cannot move a disk over 1 TB with a legacy MBR or a legacy VTOC to a previous Solaris release. EFI labeled disks continue to work as in previous Solaris releases.

For more information about the EFI label changes in this release, see EFI Disk Label.

iSNS Support in the Solaris iSCSI Target and Initiator

Solaris 10 8/07: This Solaris release provides support for the Internet Storage Name Service (iSNS) protocol in the Solaris iSCSI target and initiator software. The iSNS protocol allows for the automated discovery, management, and configuration of iSCSI devices on a TCP/IP network.

In this Solaris release, you can use the iscsitadm command to add access to an existing third-party iSNS server or you can user the Solaris iSNS server to automatically discover the iSCSI devices in your network. The iSNS server can be specified by hostname or IP address. After you add the iSNS server information, you will need to enable access to the server.

See the following resources for step-by-step instructions:

Solaris iSCSI Target Support

Solaris 10 8/07: This Solaris release provides support for iSCSI target devices, which can be disk or tape devices. Previous Solaris releases provide support for iSCSI initiators. The advantage of setting up Solaris iSCSI targets is you might have existing Fibre-Channel devices that can be connected to clients without the cost of Fibre-Channel HBAs. In addition, systems with dedicated arrays can now export replicated storage with ZFS or UFS file systems.

You can use the iscsitadm command to set up and manage your iSCSI target devices. For the disk device that you select as your iSCSI target, you'll need to provide an equivalently sized ZFS or UFS file system as the backing store for the iSCSI daemon.

After the target device is set up, use the iscsiadm command to identify your iSCSI targets, which will discover and use the iSCSI target device.

For more information, see Chapter 14, Configuring Oracle Solaris iSCSI Targets and Initiators (Tasks), iscsiadm(1M), and iscsitadm(1M).

Note –

A previous version of this guide incorrectly indicated that the Solaris iSCSI target support was available in the Solaris 10 11/06 release. This feature is available starting in the Solaris 10 8/07 release.

Solaris iSCSI Initiator Support

Solaris 10 1/06: iSCSI is an Internet Protocol (IP)-based storage networking standard for linking data storage subsystems. By carrying SCSI commands over IP networks, the iSCSI protocol enables you to mount disk devices, from across the network, onto your local system. On your local system, you can use the devices like block devices.

For more information, see Chapter 14, Configuring Oracle Solaris iSCSI Targets and Initiators (Tasks).

Solaris iSCSI Initiator Support Enhancements

Solaris 10 6/06: The following enhancements have been added to the Solaris iSCSI initiator support:

For more information about configuring Solaris iSCSI initiators, see Chapter 14, Configuring Oracle Solaris iSCSI Targets and Initiators (Tasks) and iscsiadm(1M).

x86: Disk Management in the GRUB Boot Environment

Solaris 10 1/06: The GRUB boot menu has replaced the previous method for booting an x86 system. In the area of disk management, you use the GRUB interface when booting from an alternative device to replace a system disk or when installing the bootblocks.

The GRUB boot environment provides the following features:

In the GRUB environment, you cannot use the fmthard command to install the boot blocks automatically when run on an x86 system. You must install the boot blocks separately.

For detailed feature information and instructions on using the new GRUB based booting on x86 systems, see Booting an x86 Based System by Using GRUB (Task Map) in System Administration Guide: Basic Administration.

For instructions for managing disks in the GRUB boot environment, see the following references:

This feature is not available on SPARC systems.

Support for SCSI Disks That are Larger Than 2 Terabytes

Solaris 10 1/06: The SCSI driver, ssd or sd, supports 2 terabytes and greater. The SCSI driver, ssd or sd, is limited to 2 TB in previous Solaris releases.

The format utility can be used to label, configure, and partition these larger disks. For information about using the EFI disk label on large disks and restrictions with the fdisk utility, see Restrictions of the EFI Disk Label.

Where to Find Disk Management Tasks

Use these references to find step-by-step instructions for managing disks.

Disk Management Task 

For More Information 

Format a disk and examine a disk label. 

Chapter 11, Administering Disks (Tasks)

Add a new disk to a SPARC system. 

Chapter 12, SPARC: Adding a Disk (Tasks)

Add a new disk to an x86 system. 

Chapter 13, x86: Adding a Disk (Tasks)

Hot-plug a SCSI or PCI disk. 

Chapter 6, Dynamically Configuring Devices (Tasks)

Overview of Disk Management

Managing disks in the Oracle Solaris OS usually involves setting up the system and running the Solaris installation program to create the appropriate disk slices and file systems and to install the Oracle Solaris OS. Occasionally, you might need to use the format utility to add a new disk drive or replace a defective disk drive.

Disk Terminology

Before you can effectively use the information in this section, you should be familiar with basic disk architecture. In particular, you should be familiar with the following terms:

Disk Term 

Description 

Track 

A concentric ring on a disk that passes under a single stationary disk head as the disk rotates. 

Cylinder 

The set of tracks with the same nominal distance from the axis about which the disk rotates. 

Sector 

Section of each disk platter. A sector holds 512 bytes.  

Block 

A data storage area on a disk. A disk block is 512 bytes. 

Disk controller 

A chip and its associated circuitry that controls the disk drive. 

Disk label 

The first sector of a disk that contains disk geometry and partition information. 

Device driver 

A kernel module that controls a hardware or virtual device. 

For additional information, see the product information from your disk's manufacturer.

About Disk Labels

A special area of every disk is set aside for storing information about the disk's controller, geometry, and slices. This information is called the disk's label. Another term that is used to described the disk label is the VTOC (Volume Table of Contents) on a disk with a VTOC label. To label a disk means to write slice information onto the disk. You usually label a disk after you change its slices.

The Solaris release supports the following two disk labels:

If you fail to label a disk after you create slices, the slices will be unavailable because the OS has no way of “knowing” about the slices.

EFI Disk Label

The EFI label provides support for physical disks and virtual disk volumes that are greater than 2 TB in size. This release also includes updated disk utilities for managing disks greater than 2 TB in size. The UFS file system is compatible with the EFI disk label, and you can create a UFS file system greater than 2 TB. For information on creating a multiterabyte UFS file system, see 64-bit: Support of Multiterabyte UFS File Systems.

The unbundled Sun QFS file system is also available if you need to create file systems greater than 1 TB. For information on the Sun QFS file system, see Sun QFS, Sun SAM-FS, and Sun SAM-QFS File System Administrator’s Guide.

The Solaris Volume Manager software can also be used to manage disks greater than 1 TB in this Solaris release. For information on using Solaris Volume Manager, see Solaris Volume Manager Administration Guide.

The VTOC label is still available for disks less than 2 terabytes in size. If you are only using disks smaller than 2 TB on your systems, managing disks will be the same as in previous Solaris releases. In addition, you can use the format-e command to label a disk 2 TB in size or less with an EFI label. For more information, see Example 11–6.

You can use the format -e command to apply an EFI label to a disk if the system is running the appropriate Solaris release. However, you should review the important information in Restrictions of the EFI Disk Label before attempting to apply an EFI label.

You can also use the format -e command to reapply a VTOC label if the EFI label is no longer needed. For example:


# format
Specify disk (enter its number): 2
selecting c0t5d0
[disk formatted]
.
.
.
format> label
[0] SMI Label
[1] EFI Label
Specify Label type[1]: 0
Warning: This disk has an EFI label. Changing to SMI label will erase all
current partitions.
Continue? yes
Auto configuration via format.dat[no]? 
Auto configuration via generic SCSI-2[no]? 
format> quit
Caution – Caution –

Keep in mind that changing disk labels will destroy any data on the disk.

Comparison of the EFI Label and the VTOC Label

The EFI disk label differs from the VTOC disk label in the following ways:

Restrictions of the EFI Disk Label

Keep the following restrictions in mind when determining whether using disks greater than 1 terabyte is appropriate for your environment:

Support for EFI-Labeled Disks on x86 Systems

Solaris support for the EFI disk label is available on x86 systems. Use the following command to add an EFI label on an x86 system:


# format -e
> [0] SMI Label
> [1] EFI Label
> Specify Label type[0]: 1
> WARNING: converting this device to EFI labels will erase all current
> fdisk partition information. Continue? yes

Previous label information is not converted to the EFI disk label.

You will have to recreate the label's partition information manually with the format command. You cannot use the fdisk command on a disk with an EFI label that is 2 terabytes in size. If the fdisk command is run on disk that is greater than 2 TB in size to create a Solaris partition, the Solaris partition is limited to 2 TB. For more information about EFI disk labels, see the preceding section.

Installing a System With an EFI-Labeled Disk

The Solaris installation utilities automatically recognize disks with EFI labels. However, you cannot use the Solaris installation program to repartition these disks. You must use the format utility to repartition an EFI-labeled disk before or after installation. The Solaris Upgrade and Live Upgrade utilities also recognize a disk with an EFI label. However, you cannot boot a system from an EFI-labeled disk.

After the Solaris release is installed on a system with an EFI-labeled disk, the partition table appears similar to the following:


Current partition table (original):
Total disk sectors available: 2576924638 + 16384 (reserved sectors)

Part      Tag    Flag     First Sector          Size          Last Sector
  0       root    wm                34         1.20TB           2576924636
  1 unassigned    wm                 0            0                0    
  2 unassigned    wm                 0            0                0    
  3 unassigned    wm                 0            0                0    
  4 unassigned    wm                 0            0                0    
  5 unassigned    wm                 0            0                0    
  6 unassigned    wm                 0            0                0    
  8   reserved    wm        2576924638         8.00MB           2576941021

Managing Disks With EFI Disks Labels

Use the following table to locate information on managing disks with EFI disk labels.

Task 

For More Information 

If the system is already installed, connect the disk to the system and perform a reconfiguration boot. 

SPARC: Adding a System Disk or a Secondary Disk (Task Map) or x86: Adding a System Disk or a Secondary Disk (Task Map)

Repartition the disk by using the format utility, if necessary.

SPARC: How to Create Disk Slices and Label a Disk or x86: How to Create Disk Slices and Label a Disk

Create disk volumes, and if needed, create soft partitions by using Solaris Volume Manager. Or, set up a ZFS storage pool. 

Chapter 2, Storage Management Concepts, in Solaris Volume Manager Administration Guide or Creating a ZFS Storage Pool in Oracle Solaris ZFS Administration Guide

Create UFS file systems for the new disk by using the newfs command.

SPARC: How to Create a UFS File System or x86: How to Create File Systems

Or, create a ZFS file system. 

How to Create ZFS File Systems in Oracle Solaris ZFS Administration Guide

Clone a disk with an EFI label 

Example 28–2

Troubleshooting Problems With EFI Disk Labels

Use the following error messages and solutions to troubleshoot problems with EFI-labeled disks.

Error Message

Dec  3 09:26:48 holoship scsi: WARNING: /sbus@a,0/SUNW,socal@d,10000/
sf@1,0/ssd@w50020f23000002a4,0 (ssd1):
Dec  3 09:26:48 holoship disk has 2576941056 blocks, which is too large 
for a 32-bit kernel
Cause

You attempted to boot a system running a 32-bit SPARC or x86 kernel with a disk greater than 1 terabyte.

Solution

Boot a system running a 64-bit SPARC or x86 kernel with a disk greater than 1 terabyte.

Error Message

Dec  3 09:12:17 holoship scsi: WARNING: /sbus@a,0/SUNW,socal@d,10000/
sf@1,0/ssd@w50020f23000002a4,0 (ssd1):
Dec  3 09:12:17 holoship corrupt label - wrong magic number
Cause

You attempted to add a disk to a system running an older Solaris release.

Solution

Add the disk to a system running the Solaris release that supports the EFI disk label.

About Disk Slices

Files stored on a disk are contained in file systems. Each file system on a disk is assigned to a slice, which is a group of sectors set aside for use by that file system. Each disk slice appears to the Oracle Solaris OS (and to the system administrator) as though it were a separate disk drive.

For information about file systems, see Chapter 16, Managing File Systems (Overview).

Note –

Slices are sometimes referred to as partitions. Certain interfaces, such as the format utility, refer to slices as partitions.

When setting up slices, remember these rules:

Slices are set up slightly differently on SPARC and x86 platforms. The following table summarizes the differences.

Table 10–1 Slice Differences on SPARC and x86 Platforms

SPARC Platform 

x86 Platform 

The entire disk is devoted to Oracle Solaris OS. 

Disk is divided into fdisk partitions, one fdisk partition per operating system.

VTOC – The disk is divided into 8 slices, numbered 0-7.

EFI – The disk is divided into 7 slices, numbered 0-6.

VTOC – The Solaris fdisk partition is divided into 10 slices, numbered 0–9.

EFI – The disk is divided into 7 slices, numbered 0-6

Solaris Volume Manager, previously the Solstice DiskSuite, has a partitioning feature, soft partitions. Soft partitions enable more than eight partitions per disk.

For general information about Solaris Volume Manager, see Chapter 2, Storage Management Concepts, in Solaris Volume Manager Administration Guide. For information on soft partitions, see Chapter 12, Soft Partitions (Overview), in Solaris Volume Manager Administration Guide.

Disk Slices

The following table describes the slices that might be found on a system that runs the Oracle Solaris OS.

On x86 systems:

Table 10–2 Customary Disk Slices

Slice 

File System 

Usually Found on Client or Server Systems? 

Comments 

0 

root (/)

Both 

Holds files and directories that make up the OS. 

EFI – You cannot boot from a disk with an EFI label.

1 

swap 

Both 

Provides virtual memory, or swap space.

2 

— 

Both 

VTOC – Refers to the entire disk, by convention. The size of this slice should not be changed.

EFI – Optional slice to be defined based on your site's needs.

3 

/export, for example

Both 

Optional slice that can be defined based on your site's needs. 

Can be used on a server to hold alternative versions of operating systems that are required by client systems. 

4 

 

Both 

Optional slice to be defined based on your site's needs. 

5 

/opt, for example

Both 

Optional slice to be defined based on your site's needs. 

Can be used to hold application software added to a system. If a slice is not allocated for the /opt file system during installation, the /opt directory is put in slice 0.

6 

/usr

Both 

Holds OS commands (also known as executables). This slice also holds documentation, system programs (init and syslogd, for example), and library routines.

7 

/home or

/export/home

Both 

Holds files that are created by users. 

8 

N/A 

N/A 

VTOC – Contains GRUB boot information.

EFI – A reserved slice created by default. This area is similar to the VTOC's alternate cylinders. Do not modify or delete this slice.

9 (x86 only)

— 

Both 

EFI – Not applicable.

VTOC – Provides an area that is reserved for alternate disk blocks. Slice 9 is known as the alternate sector slice.

Note –

On a disk with a VTOC label, do not modify slice or use slice 2 to store a file system. Products, such as Solaris Volume Manager, Solaris Live Upgrade, and installgrub, do not work correctly if slice 2 is modified in any way.

Using Raw Data Slices

The disk label is stored in block 0 of each disk. So, third-party database applications that create raw data slices must not start at block 0. Otherwise, the disk label will be overwritten, and the data on the disk will be inaccessible.

Do not use the following areas of the disk for raw data slices, which are sometimes created by third-party database applications:

Slice Arrangements on Multiple Disks

Although a single large disk can hold all slices and their corresponding file systems, two or more disks are often used to hold a system's slices and file systems.

Note –

A slice cannot be split between two or more disks. However, multiple swap slices on separate disks are allowed.

For instance, a single disk might hold the root (/) file system, a swap area, and the /usr file system, while another disk holds the /export/home file system and other file systems that contain user data.

In a multiple disk arrangement, the disk that contains the OS and swap space (that is, the disk that holds the root (/) and /usr file systems and the slice for swap space) is called the system disk. Other disks are called secondary disks or non-system disks.

When you arrange a system's file systems on multiple disks, you can modify file systems and slices on the secondary disks without having to shut down the system or reload the OS.

When you have more than one disk, you also increase input-output (I/O) volume. By distributing disk load across multiple disks, you can avoid I/O bottlenecks.

Determining Which Slices to Use

When you set up a disk's file systems, you choose not only the size of each slice, but also which slices to use. Your decisions about these matters depend on the configuration of the system to which the disk is attached and the software you want to install on the disk.

System configurations that need disk space are as follows:

Each system configuration can use slices in a different way. The following table lists some examples.

Table 10–3 System Configurations and Slices

Slice 

Servers 

Stand-alone Systems 

0 

root 

root 

1 

swap 

swap 

2 

— 

— 

3 

/export

— 

6 

/usr

/usr

7 

/export/home

/home

For more information about system configurations, see Overview of System Types in System Administration Guide: Basic Administration.

Note –

The Solaris installation utility provides default slice sizes based on the software you select for installation.

format Utility

Read the following overview of the format utility and its uses before proceeding to the “how-to” or reference sections.

The format utility is a system administration tool that is used to prepare hard disk drives for use on your Solaris system.

The following table shows the features and associated benefits that the format utility provides.

Table 10–4 Features and Benefits of the format Utility

Feature 

Benefit 

Searches your system for all attached disk drives 

Reports on the following:  

  • Target location

  • Disk geometry

  • Whether the disk is formatted

  • If the disk has mounted partitions

Retrieves disk labels 

Convenient for repair operations 

Repairs defective sectors 

Allows administrators to repair disk drives with recoverable errors instead of sending the drive back to the manufacturer 

Formats and analyzes a disk 

Creates sectors on the disk and verifies each sector 

Partitions a disk 

Divides a disk into slices so that individual file systems can be created on separate slices 

Labels a disk 

Writes disk name and configuration information to the disk for future retrieval (usually for repair operations) 

The format utility options are described in Chapter 15, The format Utility (Reference).

When to Use the format Utility

Disk drives are partitioned and labeled by the Solaris installation utility when you install the Solaris release. You can use the format utility to do the following:

The main reason a system administrator uses the format utility is to partition a disk. These steps are covered in Chapter 12, SPARC: Adding a Disk (Tasks) and Chapter 13, x86: Adding a Disk (Tasks).

See the following section for guidelines on using the format utility.

Guidelines for Using the format Utility

Table 10–5 format Utility Guidelines

Task 

Guidelines 

For More Information 

Format a disk. 

  • Any existing data is destroyed when you reformat a disk.

  • The need for formatting a disk drive has decreased as more and more manufacturers ship their disk drives formatted and partitioned. You might not need to use the format utility when you add a disk drive to an existing system.

  • If a disk has been relocated and is displaying many disk errors, you can attempt to reformat it. Reformatting automatically remaps any bad sectors.

How to Format a Disk

Replace a system disk. 

  • Data from the damaged system disk must be restored from a backup medium. Otherwise, the system will have to be reinstalled by using the installation utility.

SPARC: How to Connect a System Disk and Boot, x86: How to Connect a System Disk, or, if the system must be reinstalled, Oracle Solaris 10 9/10 Installation Guide: Basic Installations

Divide a disk into slices. 

  • Any existing data is destroyed when you repartition and relabel a disk with existing slices.

  • Existing data must be copied to backup media before the disk is repartitioned and restored.

SPARC: How to Create Disk Slices and Label a Disk or x86: How to Create Disk Slices and Label a Disk

Add a secondary disk to an existing system. 

  • Any existing data must be restored from backup media if the secondary disk is reformatted or repartitioned.

SPARC: How to Connect a Secondary Disk and Boot or x86: How to Connect a Secondary Disk and Boot

Repair a disk drive. 

  • Some customer sites prefer to replace rather than repair defective drives. If your site has a repair contract with the disk drive manufacturer, you might not need to use the format utility to repair disk drives.

  • The repair of a disk drive usually means that a bad sector is added to a defect list. New controllers remap bad sectors with no system interruption.

  • If the system has an older controller, you might need to remap a bad sector and restore any lost data.

Repairing a Defective Sector

Formatting a Disk

In most cases, disks are formatted by the manufacturer or reseller. So, they do not need to be reformatted when you install the drive. To determine if a disk is formatted, use the format utility. For more information, see How to Determine if a Disk Is Formatted.

If you determine that a disk is not formatted, use the format utility to format the disk.

When you format a disk, you accomplish two steps:

Caution – Caution –

Formatting a disk is a destructive process because it overwrites data on the disk. For this reason, disks are usually formatted only by the manufacturer or reseller. If you think disk defects are the cause of recurring problems, you can use the format utility to do a surface analysis. However, be careful to use only the commands that do not destroy data. For details, see How to Format a Disk.

A small percentage of total disk space that is available for data is used to store defect and formatting information. This percentage varies according to disk geometry, and decreases as the disk ages and develops more defects.

Formatting a disk might take anywhere from a few minutes to several hours, depending on the type and size of the disk.

Partitioning a Disk

The format utility is most often used by system administrators to partitioning a Disk. The steps are as follows:

The easiest way to partition a disk is to use the modify command from the partition menu of the format utility. The modify command allows 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.

Partition Table Terminology

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 describes partition table terminology.

Table 10–6 Partition Table Terminology

Partition Term 

Value 

Description 

Number 

0–7

VTOC – Partitions or slices, numbered 0–7.

EFI – Partitions or slices, numbered 0–6.

Tag 

0=UNASSIGNED 1=BOOT 2=ROOT 3=SWAP 4=USR 5=BACKUP 7=VAR 8=HOME 11=RESERVED

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 state is the default for partitions that are 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.

For more information on displaying the partition table, see the following references:

Displaying Partition Table Information

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 displayed by the format utility contains the following information.

Column Name 

Description 

Part

Partition or slice number. See Table 10–6 for a description of this column.

Tag

Partition tag. See Table 10–6 for a description of this column.

Flag

Partition flag. See Table 10–6 for a description of this column.

Cylinders

The starting and ending cylinder number for the slice. Not displayed on EFI-labeled disks. 

Size

The slice size in MB. 

Blocks

The total number of cylinders and the total number of sectors per slice. Not displayed on EFI-labeled disks. 

First Sector

EFI – The starting block number. Not displayed on VTOC-labeled disks.

Last Sector

EFI – The ending block number. Not displayed on VTOC-labeled disks.

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:

prtvtoc Column Name

Description  

Partition

Partition or slice number. For a description of this column, see Table 10–6.

Tag

Partition tag. For a description of this column, see Table 10–6.

Flags

Partition flag. For a description of this column, see Table 10–6.

First Sector

The first sector of the slice. 

Sector Count

The total number of sectors in the slice. 

Last Sector

The last sector of the slice. 

Mount Directory

The last mount point directory for the file system. 

Using the Free Hog Slice

When you use the format utility to change the size of one or more disk slices, you designate a temporary slice that will expand and shrink to accommodate the resizing operations.

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 Disk Slices and Label a Disk or x86: How to Create Disk Slices and Label a Disk.