Implementing Linux on Integrated xSeries Solutions for iSeries

Chapter 3. OS/400 operations 47

3.2 Overview

When an integrated Linux server is installed on iSeries, the following objects are created:

򐂰 Network server description (NWSD)

This is the main configuration object of an integrated server that OS/400 uses to control

the server and describe its attributes. Each integrated Linux server instance has a

corresponding NWSD. The NWSD contains the hardware resource name (LINxx) that

points the Linux server instance to a physical Integrated xSeries Server or Integrated

xSeries Adapter. All other OS/400 objects needed to run a Linux server are linked to, and

controlled by, the NWSD.

The NWSD provides independence between instances of Linux and the Intel-compatible

hardware that they run on (Integrated xSeries Server and Integrated xSeries Adapter).

This unique architecture enables some powerful functions, such as the ability to:

– Create multiple Linux server instances that can be run on the same integrated

hardware resource, although not at the same time. This provides a “dormant” server

capability.

– Switch Linux instances between integrated hardware resources. This provides a “hot

spare” backup server capability that can be quickly activated in the case of failure of an

Integrated xSeries Server or Integrated xSeries Adapter. For more information on hot

spare refer to 5.2.6, “Hot spare” on page 135.

򐂰 Server instances

Each integrated server (as shown in Figure 3-4 on page 52) or network server description

(as shown in Figure 3-2 on page 49) represents a Linux or Windows server instance,

not

an Integrated xSeries Server or Integrated xSeries Adapter.

Each server instance has a corresponding network server description (NWSD) and vice

versa. You can create multiple instances of Linux or Windows on one Integrated xSeries

Server or Integrated xSeries Adapter, although only one instance can be active at a time.

In other words, iSeries Integration for Linux and Windows separates the hardware

(Integrated xSeries Server or Integrated xSeries Adapter) from the Linux and Windows

instances that were created to run on that hardware. This is a unique feature of the iSeries

Windows and Linux integration architecture, and provides major benefits in terms of

availability and hardware rationalization.

When we are performing operations on integrated Linux servers using iSeries Navigator,

we usually talk in terms of

servers. When using CL commands through the OS/400

command line we usually talk in terms of network server descriptions or

NWSDs.

򐂰 Network server storage space

Storage spaces are chunks of iSeries disk storage that are created in an OS/400 auxiliary

storage pool (ASP) and reserved for Linux or Windows. Because storage spaces are

virtual disk drives created from OS/400 single-level storage, each storage space is

scattered across all the physical disk drives in the ASP. They can reside in the system

ASP, a user ASP, or an independent ASP (IASP), and appear as objects in the

/QFPNWSSTG IFS directory.

From an OS/400 perspective, this portion of iSeries disk storage is called a network server

storage space, or storage space for short. From the Linux (or Windows) perspective, this

portion of iSeries disk storage is seen as a physical disk drive. In fact these drives are

completely virtual, so we often refer to storage spaces and disk drives as virtual drives or

simply drives. When we are discussing integrated Linux servers we use these terms

interchangeably. Each disk drive icon (as shown in Figure 3-5 on page 53) or storage

space (as shown in Figure 3-1 on page 48) represents a Linux or Windows (virtual) disk

drive.