NAS / SAN

NAS – Network Attached Storage (Filer)

SAN – Storage Area Network

What differentiates the two?

NASWhat is a NAS?

Network attached storage (NAS) is an adding of disk drives and PC servers to existing networks to increase storage space.

NAS appliances expand storage capacity independently of the PC server and provide a simple, cost-effective solution to adding network storage.

What components make up a NAS?

Appliance, disk storage, network connection

NAS

What is a NAS appliance?

NAS appliances were developed as an alternative to the general-purpose server solely for file storage.

They are single-purpose appliances dedicated to serving files that provide a flexible and inexpensive alternative for adding storage to the workgroup.

NAS

NAS appliance hardware has been streamlined by eliminating unnecessary components, which results in significant cost savings over general-purpose servers.

For example, unlike a PC server, a NAS appliance has no need for a keyboard, mouse, monitor, or I/O ports.

NAS

NAS appliances run a highly efficient operating system, typically with built-in support for multiple networking protocols, which has been optimized for serving files on the network.

Unlike traditional servers whose operating systems charge a "per seat" licensing fee for each user connected to the server, there are no licensing fees with NAS appliances.

NAS

How does it communicate?

An appliance communicates using Network File System (NFS) for UNIX/Linux environments, Common Internet File System (CIFS) for Microsoft Windows environments, FTP, http, and other networking protocols.

NASApplications for NAS

• File sharing and online storage.• Backups

• Duplication of images for frequently used software configurations for distribution.

• Increase online storage at particular locations for remote offices.

NAS

Required/Desirable Features

• Compatibility with Existing Networks

• Easy Installation

• Intuitive Web Administration

• Network Security

• Cross-Platform File Sharing

(Cont.)

NAS

Legacy cross-platform environment

                                                                                                     

                                                                

NAS

With NAS

                                                                                                      

                             

NAS

Required/Desirable Features (Cont)

• Compatibility with Established Backup Policy

• Improved Performance under Load

• High Reliability

• Portable Storage

NAS

Benefits

• With a NAS appliance, users anywhere on the network—from corporate headquarters to remote offices—are assured of timely, reliable access to their data.

• NAS provides IT managers have a cost-effective file server that is easily integrated into an existing workgroup.

NAS / SANSimilarities:

Both provide

• optimal consolidation.

• centralized data storage.

• efficient file access.

NAS / SANSimilarities:

Both allow you to:• share storage among a number of hosts• support multiple different operating systems at the same time• separate storage from the application server.

NAS / SAN

Similarities:

Both can• provide high data availability• ensure integrity with redundant components and

redundant array of independent disks (RAID).

NAS / SANDifferences:

NAS and SAN represent two different storage technologies and they attach to your network in very different places.

NASNAS is a defined product that sits

between your application server and your file system

SANSAN is a defined architecture that sits between a file

system and an underlying physical storage It is its own network, connecting all storage and all servers.

NAS

NAS is network-centric.

NAS provides security and performs all file and storage services through standard network protocols, using TCP/IP for data transfer, Ethernet and Gigabit Ethernet for media access, and CIFS, http, and NFS for remote file service.

SAN

A SAN is data-centric - a network dedicated to storage of data. Unlike NAS, a SAN is separate from the traditional LAN or messaging network. Therefore, a SAN is able to avoid standard network traffic, which often inhibits performance.

SANs employ gateways, switches, and routers to facilitate data movement between heterogeneous server and storage environments.

NAS / SAN

NAS is file oriented

SAN is SCSI block oriented

NAS is simple to install (Plug and Play)

SAN is complex

SAN

What is a SAN? A SAN consists of a dedicated network that interconnects servers and their applications to storage resources with the use a switch or hub. (Hubs seldom seen any more.)

Storage resources usually consists of disks and tapes.

The dedicated network is usually fibre channel or iSCSI

SAN

An adapter card on the server is connected by fiber optic or copper cabling to a SAN switch.

Disk arrays and tape devices are also connected to the switch, which brings all servers and storage devices into a peer-to-peer network.

SAN

NAS

NAS

NAS

NAS

SAN

SAN

SAN

How can SAN accommodate a mixed computing environment (UNIX, WINDOWS, NOVELL)?

Through a technique called zoning.

SAN

SAN

A method of subdividing a storage area network into disjoint zones, or subsets of nodes on the network. Storage area network nodes outside a zone are invisible to nodes within the zone. Moreover, with switched SANs, traffic within each zone may be physically isolated from traffic outside the zone.

SANWhat type of network access does SAN

employ?

Fibre channel

iSCSI

Infiniband

CIM (Common Information Model)

Bluefin (based on CIM)

Fibre ChannelWhat is fibre channel?

Fibre channel is a high performance serial link supporting its own, as well as higher level protocols such as the FDDI, SCSI, HIPPI and IPI

It is neither a fiber or a channel.

Fibre Channel is the general name of an integrated set of standards developed by the American National Standards Institute (ANSI).

Fibre ChannelWhat is a channel?

There are two basic types of data communication between processors and between processors and peripherials: channels and networks.

A channel provides a direct or switched point-to-point connection between the communicating devices.

A channel is typically hardware-intensive and

transports data at the high speed with low overhead.

.

Fibre Channel

A network is an aggregation of distributed nodes (like workstations, file servers or peripherials) with it's own protocol that supports interaction among these nodes.

Fibre Channel

A network is an aggregation of distributed nodes (like workstations, file servers or peripherials) with it's own protocol that supports interaction among these nodes.

Networks can handle a more extensive range of

tasks than channels as they operate in an environment of unanticipated connections, while channels operate amongst only a few devices with predefined addresses.

Fibre Channel

Fibre Channel attempts to combine the best of these two methods of communication into a new I/O interface that meets the needs of channel users and also network users.

It allows for an active intelligent interconnection scheme, called a Fabric, to connect devices.

Fibre Channel

In Fibre Channel terms the switch connecting the devices is called Fabric.

The link is the two unidirectional fibres transmitting to opposite directions with their associated transmitter and receiver.

Each fibre is attached to a transmitter of a port at one end and a receiver of another port at the other end.

Fibre Channel

When a Fabric is present in the configuration, the fibre may attach to a node port (N_Port) and to a port of the Fabric (F_Port).

Fibre Channel

FC is structured as a set of hierarchical functions.

Fibre Channel

The lowest level (FC-0) defines the physical link in the system, including the fibre, connectors, optical and electrical parameters for a variety of data rates.

(133 Mbit/s, 266 Mbit/s, 530 Mbit/s, and 1 Gbits/s) and on three types of both electrical and optical media.

The system bit error rate (BER) at the supported media and speeds is less than 10exp-12 [1].

Fibre Channel

FC-1 defines the transmission protocol including serial encoding and decoding rules, special characters and error control. The information transmitted over a fibre is encoded 8 bits at a time into a 10 bit Transmission Character.

Fibre ChannelThe Signaling Protocol (FC-2) level serves as the

transport mechanism of Fibre Channel. The framing rules of the data to be transferred between ports, the different mechanisms for controlling the three service classes and the means of managing the sequence of a data transfer are defined by FC-2. To aid in the transport of data across the link, the following building blocks are defined by the standard:

• Ordered Set • Frame • Sequence • Exchange • Protocol

Fibre ChannelThe Frame Header is used to control link applications, control device protocol transfers, and detect missing or out of order Frames. An optional header may contain further link control information.

Fibre ChannelA maximum 2112 byte long field (payload) contains the information to be transferred from a source N_Port to a destination N_Port.

Fibre ChannelTo ensure efficient transmission of different types

of traffic, FC defines three classes of service.

Class 1 is a service which provides dedicated connections, in effect providing the equivalent of a dedicated physical connection. Once established, a Class 1 connection is retained and guaranteed by the Fabric. This service guarantees the maximum bandwidth between two N_Ports, so this is the best for sustained, high throughput transactions. In Class 1, Frames are delivered to the destination Port in the same order as they are transmitted. Figure 5 shows the flow control management of a Class 1 connection.

Fibre Channel

Fibre ChannelClass 2 is a Frame-switched, connectionless service

that allows bandwidth to be shared by multiplexing Frames from multiple sources onto the same channel or channels. The Fabric may not guarantee the order of the delivery and

Frames may be delivered out of order.

If delivery cannot be made due to congestion, a Busy frame is returned and the sender tries again.

Fibre Channel

Fibre Channel

• Class 3 service is identical to Class 2, except that the Frame delivery is not confirmed. (Flow control is managed only on buffer level) This type of transfer, known as datagram provides the quickest transmission by not sending

confirmation.

Fibre Channel

Fibre ChannelThe FC-3 level of the FC standard is intended to

provide the common services required for advanced features such as:

• Striping -To multiply bandwidth using multiple N_ports in parallel to transmit a single information unit across multiple links.

• Hunt groups - The ability for more than one Port to respond to the same alias address. This improves efficiency by decreasing the chance of reaching a busy N_Port.

• Multicast - Multicast delivers a single transmission to multiple destination ports. This includes sending to all N_Ports on a Fabric (broadcast) or to only a subset of the N_Ports on a Fabric.

Fibre ChannelFC-4, the highest level in the FC structure

defines the application interfaces that can execute over Fibre Channel. It specifies the mapping rules of upper layer protocols using the FC levels below

Three IP SAN TransportsThe three IP storage networking transports are

significantly different, but they all provide a common function: transporting block-level storage over an IP network. All three transports enable end users to

• Leverage existing storage devices (SCSI and Fibre Channel) and networking infrastructures (Gigabit Ethernet);

• Maximize storage resources to be available to more applications;

• Extend the geographical limitations of DAS and SAN access;

• Use existing storage applications (backup, disaster recovery, and mirroring) without modification; and

• Manage IP-based storage networks with existing tools and IT expertise.

iSCSI

The Internet Small Computer Systems Interface (iSCSI) protocol defines the rules and processes to transmit and receive block storage applications over TCP/IP networks by encapsulating SCSI commands into TCP and transporting them over the network via IP.

FCIP

Fibre Channel over TCP/IP (FCIP) provides a mechanism to "tunnel" Fibre Channel over IP-based networks. This enables the interconnection of Fibre Channel SANs, with TCP/IP used as the underlying wide-area transport to provide congestion control and in-order delivery of data.

iFCP

The Internet Fibre Channel Protocol (iFCP) supports Fibre Channel Layer 4 FCP over TCP/IP. It is a gateway-to-gateway protocol where TCP/IP switching and routing components complement and enhance, or replace, the Fibre Channel fabric.

iFCP

The Internet Fibre Channel Protocol (iFCP) supports Fibre Channel Layer 4 FCP over TCP/IP. It is a gateway-to-gateway protocol where TCP/IP switching and routing components complement and enhance, or replace, the Fibre Channel fabric.

iSCSIiSCSI (Internet Small Computer System

Interface) is a TCP/IP-based protocol for establishing and managing connections between IP-based storage devices, hosts and clients. SNIA - IP Storage Forum: http://www.snia.org/

iSCSI describes:  • Transport protocol for SCSI which

operates on top of TCP  • New mechanism for encapsulating SCSI

commands on an IP network • Protocol for a new generation of data

storage systems that natively use TCP/IP

NAS / SAN

SAN