IBM Tape Solutions for Storage Area Networks and FICON

4 IBM Tape Solutions for Storage Area Networks and FICON

1.2 Storage networks

As the era of hard-wired computer screens sitting on managers’ desks gave way to pervasive

mobile computing with the advent of local area networks (LANs) and wide area networks

(WANs), the rigid inflexibility of direct attached storage is rapidly being superseded by flexible

storage networks. Today’s enterprise IT planners need to link many users of multivendor,

heterogeneous systems to multivendor shared storage resources. They need to allow those

users to access common data, wherever it is located in the enterprise. These requirements

imply a network solution.

Two types of network storage solutions are now available:

򐂰 Network Attached Storage (NAS)

򐂰 Storage area network

It is important that you realize that NAS and SAN are not mutually exclusive. In fact, they are

both likely to be found performing different functions within the same company. The

differentiation between the two is becoming more blurred with the introduction of SCSI over

the Internet Protocol (iSCSI) and NAS bridges or gateways. After looking at NAS and SAN

separately, we attempt to position them.

1.2.1 Network Attached Storage

NAS solutions use the LAN in front of the server. They transmit data over the LAN using

messaging protocols, such as Transmission Control Protocol/Internet Protocol (TCP/IP) and

NetBIOS. Figure 1-2 illustrates this.

Figure 1-2 Network Attached Storage

By making storage devices LAN addressable, the storage is freed from its direct attachment

to a specific server. In principle, any user running any operating system can address the

storage device by means of a common access protocol, such as Network File System (NFS),

a fundamental point of difference between NAS and iSCSI. In addition, a task, such as

backup to tape, can be performed across the LAN, enabling sharing of expensive hardware

resources between multiple servers. Most storage devices cannot attach to a LAN. NAS

appliances are specialized file servers that are designed for this type of attachment.

Local/Wide-Area Network

(Messaging Protocol - TCP/IP, Net

BIOS)

Intelligent Disk Array

JBOD

IBM 3466 (NSM)

Network Storage Manager

Network Backup Server

Clients

Clients

Web

Server

Application

Server

Database

Server