User`s guide

Using Logical Disks

You can subset your physical disks into smaller logical disks to group together similar

ﬁles in one place or if you have a large disk and cannot use all the space on that

disk. The chapter Using the Logical Disk (LD) Utility in the Introduction to RT–11

explains how to use logical disks.

Note: Do not confuse logical disks with logical-device names. They are similar in

name, but are completely different. You can, however, assign logical-device names

to specify logical disks.

Using a Virtual Disk

A virtual or VM (Virtual Memory) disk is an area in extended memory that you

conﬁgure as a disk. The chapter on the virtual memory device in the Introduction

to RT–11 describes that device.

When you use a physical disk, your computer must periodically read and write code

between the computer’s memory and disk. But when you use a virtual disk, your

computer reads and writes code between segments of memory.

Two advantages of using a virtual disk are:

• It lets you take advantage of memory space in your computer which you might

not otherwise use.

• It can increase the speed of your computer, making your programs run more

efﬁciently.

You should not use a virtual disk to store the only copy of ﬁles you need to keep,

since the disk lasts only as long as the computer is turned on. However, you can

copy ﬁles to a virtual disk and even boot your operating system from that disk, once

you have ﬁrst booted the operating system on a physical disk. See the Introduction

to RT–11 for that procedure. Then, you can use the virtual disk as a work-space

disk.

3–4 Using RT–11 Commands