1 Introduction to Sharing Software

This chapter introduces software sharing and the components that make up a software sharing environment. This chapter includes the following topics:

Software sharing concepts, components, and benefits (Section 1.1)

Describing the software sharing environment (Section 1.2)

Identifying your CD-ROM drive's device name (Section 1.3)

1.1 Overview

A server is a computer system that provides another computer system with required or useful information or resources. The system that uses the information or resources from the server is called a client. A given server can serve one or many clients. Computers in a network can share disk space, lists of names, software kits, processing services, and other entities.

For sharing software using Remote Installation Services (RIS) and Dataless Management Services (DMS), the server supplies software, software kits, and disk space for clients to use.

The RIS and DMS services let you share software in the following ways:

RIS sets up a system where one or more installable software kits are stored for installation across a local area network (LAN). With RIS, one computer, the RIS server, stores the kit in a special area (called the RIS area) on its disk. Other computers, called RIS clients, can install the software onto their own disks by accessing it across the network instead of from locally mounted distribution media (such as CD-ROM).

DMS sets up a system where you can save disk space by sharing the actual operating system software between computers. Without DMS, each computer has a copy of its operating system software on its own disk. With DMS, one computer, acting as a DMS server, stores the software in a special area (called the DMS area) on its disk. Other computers, called DMS clients, run by accessing the software across the local area network (LAN) instead of from their local disks.

Note

DMS is not supported in a clusters environment.

The RIS and DMS utilities share architectural similarities; the primary differences are in the contents of their respective server disk areas.

The following list illustrates some of the benefits of sharing software:

You can reduce your software and hardware costs by sharing software between computers.

You are not limited to sharing one piece of software; you can share virtually all of your operating system software.

When you share software with RIS, you have a central location for all the software to install on your system and can install the same software simultaneously on several clients.

When you share software with DMS, several of the computers in your local area network (LAN) use a single copy of a given piece of software. This reduces the need for multiple copies of the same software, reduces the disk space required for software storage, and allows central administration of software resources.

1.2 Understanding the Software Sharing Environment

The following components make up the environment for software sharing:

A server

The server's system administrator prepares the server for RIS or DMS by creating the RIS or DMS areas on the server and ensuring that the server is connected to a LAN. A single server can serve both RIS and DMS clients, however a client cannot be registered to both RIS and DMS.

A distribution device on the server

For most servers, the distribution device is a CD-ROM drive or a software distribution copied directly to magnetic disk. You transfer or link the software subsets for one or more specific products and architectures from the distribution media to the RIS or DMS areas on the server. Registered clients can then access the software.

A local area network (LAN)

You must set up the server and all client processors as hosts on the LAN (using Ethernet, FDDI, or Token Ring for RIS and Ethernet or FDDI for DMS). Clients use the LAN to access the server's RIS and DMS areas.

Clients

RIS clients are systems that can run the operating system for which the server provides kits. RIS clients also must be capable of booting over Ethernet or FDDI using the BOOTP and TFTP protocols to install the base operating system from a server. Layered products can be installed after the client's operating system is running with the SysMan Menu.

DMS clients must be capable of booting over Ethernet or FDDI using the BOOTP and TFTP protocols. Most Alpha workstations and servers have this capability, but some data center servers cannot be configured as DMS clients. See your system's user guide and related documentation to determine whether it supports BOOTP and TFTP over Ethernet or FDDI.

Note

You cannot use RIS or DMS to install software on DEC 2000 series or DEC 7000 series servers.

1.3 Identifying a CD-ROM Drive Device Name

There are many circumstances when you need to specify your CD-ROM drive's device name and you do not know the unit number of the CD-ROM drive. How you identify this unit number depends on whether your system is running a version of the operating system that uses traditional device naming conventions or newer device naming conventions.

Use one of the following procedures to determine your CD-ROM drive's unit number:

If you are using an older version of the operating system that uses traditional device naming conventions (/dev/rrzNc), use the file command, specifying the raw device, as shown in the following example:
```
# file /dev/rrz*c
/dev/rrz1c: char special (8/1026) SCSI #0 RZ25 disk #8 (SCSI ID #1)
/dev/rrz2c: char special (8/2050) SCSI #0 RZ25 disk #16 (SCSI ID #2)
/dev/rrz3c: char special (8/3074) SCSI #0 RZ25 disk #24 (SCSI ID #3)
/dev/rrz4c: char special (8/4098) SCSI #0 RRD43 disk #32 (SCSI ID #4)
/dev/rrz9c: char special (8/17410) SCSI #1 RZ57 disk #72 (SCSI ID #1)
#
```
In the previous example, the CD-ROM device corresponds to the RRD device RRD43, and the CD-ROM drive's unit number is 4. The raw device name is /dev/rrz4c.
To mount the device, insert the CD-ROM into the drive and use a mount command, specifying the character special device, similar to the following:
```
# mount -rd /dev/rz4c /mnt
```
The previous example uses a CD-ROM drive that is unit 4 and specifies /mnt as the mount point.

If you are using a later version of the operating system that uses newer device naming conventions (/dev/disk/cdromNc), use the ls command as shown in the following example:
```
# ls -l /dev/disk/cdrom*
brw-------   1 root     system    19, 69 Nov 18 06:11 /dev/disk/cdrom0a
brw-------   1 root     system    19, 71 Nov 18 06:11 /dev/disk/cdrom0c
#
```
The CD-ROM drive's unit number is 0, and in the character special device name in this example is /dev/disk/cdrom0c. Raw devices have the same name but reside in the /dev/rdisk directory.
To mount the device, insert the CD-ROM into the drive and use a mount command similar to the following:
```
# mount -rd /dev/disk/cdrom0c /mnt
```
This example uses a CD-ROM drive that is unit 0 and specifies /mnt as the mount point.

If you have multiple CD-ROM drives and are not sure which drive corresponds to which device name, use the hwmgr command to flash the light on the drive.
For example, if you want to determine which CD-ROM drive corresponds to /dev/disk/cdrom0c and you have two CD-ROM drives, place CD-ROMs in both drives and enter the following command:
```
# hwmgr -flash light -dsf /dev/disk/cdrom0c
 
 
```
You see the light on cdrom0c blink for 30 seconds.
See hwmgr(8) for more information.