Managing Disks (Overview)
This chapter provides overview information about 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 33, SPARC: Adding a Disk (Tasks) or Chapter 34, IA: Adding a Disk (Tasks).
What's New in Disk Management?
This section describes new disk management features in the Solaris 9 release.
Solaris Volume Manager and Soft Partitioning
The previously unbundled Solstice DiskSuite™ product is now part of the Solaris 9 release and is called Solaris Volume Manager. Solaris Volume Manager's new partitioning feature, soft partitioning, enables more than eight partitions per disk.
For general information about Solaris Volume Manager, see "Storage Management Concepts" in Solaris Volume Manager Administration Guide. For information on soft partitioning, see "Soft Partitions (Overview)" in Solaris Volume Manager Administration Guide.
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 | |
Add a new disk to a SPARC system | |
Add a new disk to an IA system | |
Hot-Plug a SCSI or PCI disk |
Overview of Disk Management
The management of disks in the Solaris environment 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 operating system. Occasionally, you might need to use the format utility to add a new disk drive or replace a defective one.
Note - The Solaris operating environment runs on two types of hardware, or platforms--SPARC and IA. The Solaris operating environment runs on both 64-bit and 32-bit address spaces. The information in this document pertains to both platforms and address spaces unless called out in a special chapter, section, note, bullet, figure, table, example, or code example.
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 | A data storage area on a disk, or sections of each disk platter. A sector holds 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 device driver is a kernel module that controls a hardware or virtual device. |
For additional information, see the product information from your disk's manufacturer.
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 operating system (and to the system administrator) as though it were a separate disk drive.
For information about file systems, see Chapter 37, Managing File Systems (Overview).
Note - Slices are sometimes referred to as partitions. This book uses slice but certain interfaces, such as the format utility, refer to slices as partitions.
When setting up slices, remember these rules:
Each disk slice holds only one file system.
No file system can span multiple slices.
Slices are set up slightly differently on SPARC and IA platforms. The following table summarizes the differences.
Table 31-1 Slice Differences on Platforms
SPARC Platform | IA Platform |
|---|---|
Whole disk is devoted to Solaris environment | Disk is divided into fdisk partitions, one fdisk partition per operating environment |
Disk is divided into 8 slices, numbered 0-7 | The Solaris fdisk partition is divided into 10 slices, numbered 0-9 |
SPARC: Disk Slices
On SPARC based systems, Solaris defines eight disk slices and assigns to each a conventional use. These slices are numbered 0 through 7. The following table summarizes the contents of the eight Solaris slices on a SPARC based system.
Table 31-2 SPARC: Customary Disk Slices
Slice | File System | Usually Found on Client or Server Systems? | Purpose |
|---|---|---|---|
0 | root (/) | Both | Holds files and directories that make up the operating system. |
1 | swap | Both | Provides virtual memory, or swap space. Swap space is used when running programs are too large to fit in a computer's memory. The Solaris operating environment then "swaps" programs from memory to the disk and back, as needed. |
2 | -- | Both | Refers to the entire disk, by convention. This slice is defined automatically by the format utility and the Solaris installation programs. The size of this slice should not be changed. |
3 | /export | Server only | Holds alternative versions of the operating system. These alternative versions are required by client systems whose architectures differ from that of the server. Clients with the same architecture type as the server obtain executables from the /usr file system, usually slice 6. |
4 |
|
| Optional slice to be defined based on your site's needs. |
5 |
|
| 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 operating system 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. |
IA: Disk Slices
On IA based systems, disks are divided into fdisk partitions. An fdisk partition is a section of the disk that reserved for a particular operating environment, such as the Solaris release.
The Solaris release places ten slices, numbered 0-9, on a Solaris fdisk partition as shown in the following table.
Table 31-3 IA: Customary Disk Slices
Slice | File System | Usually Found on Client or Server Systems? | Purpose |
|---|---|---|---|
0 | root (/) | Both | Holds the files and directories that make up the operating system. |
1 | swap | Both | Provides virtual memory, or swap space. Swap space is used when running programs are too large to fit in a computer's memory. The Solaris operating environment then "swaps" programs from memory to the disk and back, as needed. |
2 | -- | Both | Refers to the entire disk, by convention. This slice is defined automatically by the format utility and the Solaris installation programs. The size of this slice should not be changed. |
3 | /export | Server only | Holds alternative versions of the operating system. These alternative versions are required by client systems whose architectures differ from that of the server. |
4 |
|
| Optional slice to be defined based on your site's needs. |
5 |
| 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 operating system 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 | -- | Both | Contains information necessary for to boot the Solaris environment from the hard disk. The slice resides at the beginning of the Solaris fdisk partition (although the slice number itself does not indicate this fact), and is known as the boot slice. |
9 | -- | Both | Provides an area that is reserved for alternate disk blocks. Slice 9 is known as the alternate sector slice. |