1. Network Attached Storage Overview
Introduction
This lesson discusses a number of component technologies in Network Attached Storage (NAS). These discussions cover the definition of NAS, functions, components, protocols, and advantages of NAS.
Importance
Understanding the basics of NAS is important to the Cisco Systems Engineer (SE) working in the storage field in order to understand the relationship of NAS to other storage technologies such as SAN and DAS.
© 2003, Cisco Systems, Inc. All rights reserved. 1

2. Lesson Objectives
Upon completion of this lesson, you will define Network Attached Storage and explain its components, protocols and advantages.
Performance Objective
Upon completion of this lesson, you will define Network Attached Storage and explain its components, protocols and advantages.
Enabling Objectives
Define NAS and indicate how a NAS device functions in a storage environment
Explain the components of a NAS, including client systems and the filer
List the protocols used in a NAS environment
Explain the advantages of NAS architectures

3. Outline What is Network Attached Storage? NAS Components NAS Protocols
NAS Advantages
Summary
Prerequisites
Curriculum Unit 1, Module 1 lesson "Direct Attached Storage."

4. What is Network Attached Storage?
Catalyst Switch
Intranet
NAS Filer
Gigabit Ethernet
CIFS
Tape
Internet
UNIX
Linux
Gigabit Ethernet
NAS = Network Attached Storage
NAS devices are network attached “appliances”
NAS is the attachment of storage devices to the Local Area Network (LAN)
What is Network Attached Storage?
Objective
Define NAS and indicate how a NAS device functions in a storage environment.
Introduction
This section explains what NAS is and includes a graphical representation of a typical NAS.
Facts
NAS is the attachment of storage devices to the Local Area Network (LAN) infrastructure. Each NAS device is a file server with either internal or external storage devices. Unlike DAS and SAN, communication between clients and the NAS device occurs at the file level using file level protocols such as the Common Internet File System (CIFS) or the Network File System (NFS).
A dedicated NAS File Server may provide storage for many different users and many different applications. If all the files were stored in one place, it would quickly become difficult to locate files, to provide privacy and protection from unauthorized access, and to provide security though data management and backup. Located files in different folders on a common disk drive may not provide sufficient privacy and protection. Files servers can provide the ability to make a physical disk drive appear as more than one logical drive. This is called storage partitioning. The logical disk drive partitions can be made accessible only to selected clients and made inaccessible to all other clients. This provides a high level of data security and privacy.

5. Notes continued from previous page
What is Network Attached Storage? (cont.)
Facts
A NAS device is a network attached appliance: it is optimized for file-based access to shared storage over a network.
The example displays a number of different clients and storage devices attached to the network. Note that a client's existing network could be a LAN within an installation, a corporate intranet or the internet. In most cases, the network would be based on Ethernet, but any network technology could be used (for example, Token Ring, FDDI, wireless, etc.).
NAS devices are really dedicated file servers. They may be based on a general-purpose computer platform, such as a PC, or on a specialized platform.
The primary reason behind the development of NAS was to enable a number of users or clients to share access to the same storage device and data. This facilitates collaborative data sharing in workgroups, departments, or organizations that need a common repository for their shared data. NAS is suitable for applications involving file serving/sharing. NAS may be used for high performance access, data protection, and disaster recovery. By using Access Control Lists (ACLs) or other mechanisms, NAS is capable of storage partitioning
Practice Items
What is the difference between a NAS device and a DAS device?

6. NAS with integrated storage
NAS Components
A NAS configuration consists of:
Client systems or servers that connect to a LAN using Network Interface Cards (NICs)
NAS storage devices
File-level protocols used to access files on the NAS devices
File-Level Requests
FC Switch
NAS with integrated storage
IP4700 GE
NAS
with external
Fibre Channel storage
Windows NT Web Farm
UNIX servers
Workstation
CIFS
NFS
NAS Components
Objective
Explain the components of a NAS, including client systems and the Filer.
Introduction
This section describes both the physical components that make up a typical NAS solution and the architectural structures, or building blocks, that help define the differences between NAS and other storage solutions.
Facts
A NAS configuration consists of:
Client systems or servers that connect to a LAN using Network Interface Cards (NICs)
The LAN
NAS storage devices
File-level protocols are used to access files on the NAS devices.

7. NAS with integrated storage
NAS Components (cont.)
Client systems
Clients originate file-level operations with the NAS storage devices
Run one or more applications
Run an operating system that manages file access
The operating system supports a network file system (NFS or CIFS)
File-Level Requests
FC Switch
NAS with integrated storage
IP4700 GE
NAS
with external
Fibre Channel storage
Windows NT Web Farm
UNIX servers
Workstation
CIFS
NFS
NAS Components (cont.)
Facts
The client must explicitly mount the file system from the NAS for CIFS and Unix. Clients originate file-level operations with the NAS storage devices. They run one or more applications and run an operating system that manages file access. The operating system supports a network file system (NFS or CIFS).
Practice Items
What are the basic components of a NAS system?

8. NAS with integrated storage
NAS Components (cont.)
The Filer connects to the IP network
File-Level Requests
NAS with integrated storage
IP4700 GE
Windows NT Web Farm
UNIX servers
Workstation
CIFS
NFS
EMC Celerra
NAS Components (cont.)
Facts
The Filer connects to the IP network The storage devices used in a NAS are similar to those used in other environments: Redundant Array of Independent Disks (RAID), and Just a Bunch of Disks (JBOD).
The Filer grants permissions for network data access.
NFS uses mount points and CIFS network shares.

9. NAS with integrated storage
NAS Protocols
Client systems require a protocol to communicate with NAS devices:
Windows systems use the Common Internet File System (CIFS) protocol
Unix systems (and others) use the Network File System (NFS)
File-Level Requests
FC Switch
NAS with integrated storage
IP4700 GE
NAS
with external
Fibre Channel storage
Windows NT Web Farm
UNIX servers
Workstation
CIFS
NFS
NAS Protocols
Objective
List the protocols used in a NAS environment.
Introduction
This section describes the protocols used in typical NAS environments.
Facts
In order for clients to access data stored on the NAS device, two main file-level protocols have been developed. In the Windows world, CIFS is used while in the Unix and Linux environments, the NFS protocol is used. These protocols enable clients to create files, read files, write files, and delete files on the NAS device.
Other protocols, such as the Direct Access File System (DAFS) may be used in the future.
Note: Be careful not to confuse the file-level protocols with lower-level protocols used by the physical interfaces for example, FC or Ethernet physical interface protocols.
Practice Items
List and explain the protocols used to communicate with NAS devices.

10. NAS Advantages Consolidation reduces the cost of managing data
Leverages existing IP infrastructure and expertise
LAN distances are greater than DAS interface support
LAN provides greater connectivity than DAS interfaces
NAS enables heterogeneous data sharing
No single point of failure
NAS Advantages
Objective
Explain the advantages of NAS architectures.
Introduction
This section describes the advantages of NAS solutions.
Facts
Consolidation - NAS permits more that one client to access shared data on the NAS device. This facilitates collaborative data sharing, and a centralized repository for shared files. Having a central storage location can also improve storage utilization. By consolidating storage on a file server, the redundant copies of application software and corporate data files are eliminated, and each PC does not require as much free space for future expansion.
As the use of computers in businesses has increased, the manpower required to keep programs up to date, to keep every user’s computers loaded with the most current company data files, and to secure those files through regular backups has also increased. Keeping program files and data files on a central storage location, the NAS storage device allows management and security of files to occur at a central location.
With NAS, space can be allocated to servers as required, but with DAS:
Space is determined by the physical storage devices
Some servers may have large amounts of unused space while others are critically low on free space
There is no way to reallocate space from one server to another without physically moving the disk drive

11. Notes continued from previous page
NAS Advantages (cont.)
Facts
Leverage - A key advantage of NAS solutions is the ability to leverage the existing network components, infrastructure and experience. NAS was developed to use existing LANs. LAN and NAS technologies are mature and generally well understood by administrators.
Distances - LAN distances are greater than DAS interfaces support—storage can be separated from the client system or server.
Connectivity - The LAN provides greater connectivity than DAS interfaces—many more devices can be connected to a LAN versus what can be connected using DAS.
Data sharing - NAS enables data sharing. Clients on the LAN can have access to files and storage space on NAS devices, subject to the administrator setting up the proper permissions. Both NFS and CIFS support NAS file sharing.
No single point of failure - NAS devices may be configured with multiple network paths so than no single point of failure in the LAN exists.
Practice Items
List and explain four advantages of NAS.

12. NAS Components Practice
Practice - NAS Components
Instructions
Label the diagram
Explain the components of a NAS, including client systems and the Filer

13. Network Attached Storage Practice
Gigabit Ethernet
Gigabit Ethernet
Practice - What is Network Attached Storage?
Instructions
Label the components in the diagram.
Indicate the role of NAS devices in a LAN

14. Lesson Practice
Discuss the following questions. Be prepared to summarize and share your answers for the class.
Define what is meant by the term “appliance”. Why are NAS devices considered appliances?
Which client protocol is used by UNIX clients to access a Network Attached Storage (NAS) device?
Network File System (NFS)
Common Internet File System (CIFS)
Intranetworking File System (IFS)
Data Transfer File System (DTFS)
Define what is meant by the term “NAS Head”
Is there a difference between a “File Server” and a “NAS Filer”?
Can Window’s clients use the CIFS protocol to access a Unix server?
NAS Lesson Practice

15. Summary This lesson presented these key points:
NAS = Network Attached Storage
The two main components of NAS are client systems and filers
The NAS Protocols are CIFS and NFS
NAS has a number of advantages over DAS, including consolidation, and the ability to leverage existing IP infrastructures.
Summary: NAS Overview
Review
This lesson covered the basics of NAS storage systems. This lesson discussed a number of component technologies in Network Attached Storage (NAS). These discussions covered the definition of NAS, functions, components (client systems and filers), protocols (NFS and CIFS), and advantages of NAS.