Mass storage devices overview

Creating disk partitions and slices

We commonly use the word ``partition'' to refer to two concepts:

A UnixWare partition is subdivided into ``slices'' which are used to define filesystems, swap area(s), and dump slices. The assignment of slices to these functions is recorded in the Volume Table of Contents (VTOC).

Just as the noun ``partition'' refers to both a portion of the disk and a subdivision of that partition, the verb ``partition'' also points to two steps:

The phrase ``partitioning the disk'' is used by many people to refer to both steps. To avoid confusion, we differentiate between the two by using the terms ``partition the disk'' and ``defining slices.'' Additional information about partitions and slices is available in vtoc(7).

Hard disk partitioning

A single hard disk can support multiple operating systems but not in the same space on that disk. You have the choice of either using all the space on your hard disk for UnixWare or dividing the hard disk into a maximum of four segments, called partitions. Each partition can hold a separate operating system. For example, you could have a UnixWare system partition, a SCO OpenServer system partition, an OS/2 partition, and a DOS partition.

NOTE: For each disk on the system, all disk space that will be used for UnixWare must be in the same partition on the disk.

Carefully consider the type, number and size of partitions you want on your system before creating them; changing them later requires that existing partitions and data be destroyed. When creating partitions, note that:

Your first opportunity to create partitions comes during the initial system load (ISL) of your UnixWare system. At that time, you can define partitions and slices for each of two hard disks, a primary and a second hard disk. When you install UnixWare on an existing system you are asked whether you want to keep the existing partitioning scheme (the default scheme) or create a new one. If you are installing on a new machine, the default scheme is one partition (partition #1), which uses 100 percent of each disk for UnixWare.

If you add a hard disk after ISL, use the diskadd(1M) command to create the partitions and slices. See ``Adding hard disks''.

Changing hard disk partitions

Changing the number or size of hard disk partitions destroys existing partitions and data on the disk being re-partitioned. If you must change your hard disk partitions, be sure to back up your data first (back up each partition on the disk).

Changing the active partition

Only one partition can be active at a time. There are two ways to change the active partition.

Defining slices

Each VTOC on a UnixWare partition can contain up to 184 slices (numbered from 0 through 183). Slices can be allocated as filesystems, swap area(s) or dump slices.

The slices on your hard disk(s) are initially assigned as part of the initial system load (ISL) process.

See the Getting Started Guide and vtoc(7) for more information about defining slices during ISL.

If you add a hard disk after ISL, use the diskadd(1M) command to create the slices. See ``Adding hard disks''.

Guidelines for defining slices

The following information from the Getting Started Guide provides guidelines for defining slices and filesystems.

Do you need to reassign slices?

After your system has been in operation for a while determine whether the allocation of slices (as reflected in the VTOC definition) is appropriate. Does it meet the needs of your users? Consider whether system performance might be improved by a larger number of smaller filesystems than you currently have, or by allocating filesystems to different hard disks. Begin by analyzing how well your system performs with the existing filesystem arrangement. See ``Managing system performance'' for a description of the sar(1M) command that evaluates performance.

If you frequently get console messages warning of insufficient memory, the amount of main memory or the swap area configuration may be insufficient to support users' demands. Before adding more main memory, try expanding the swap area. See ``Adding swap space''.

Reassigning slices

Before you reassign slices on a boot disk, do a full system backup. To reassign slices on the boot disk, you must reinstall UnixWare.

Use the disksetup(1M) command to reassign slices on disks other than the boot disk.

Next topic: Adding hard disks
Previous topic: Adding or removing hardware controllers

© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 22 April 2004