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Stratix GX in Storage Applications White Paper ®
White Paper
Stratix GX in Storage Applications
November 2002, ver. 1.0
1
WP-STXSTRAPP-1.0
Introduction
The storage market is driven by a convergence of storage and networking technologies, information growth, and
advances in storage and infrastructure bandwidth. The traditional lines between networking and storage are blurring
due to the increased adoption rate of networked storage. There are two main architectures for storage networking:
Storage Area Network (SAN) and Network Attached Storage (NAS).
The SAN architecture efficiently uses storage assets by decoupling server and storage capacities from a dedicated
network. A SAN inserts a dedicated storage network between servers and various storage subsystems. The storage
network is composed of switches that connect servers and storage.
The NAS architecture uses software to resolve storage challenges. NAS uses existing server technologies and
networking technologies (Ethernet) and adds file intelligence. Unlike SANs, where data is managed by traditional
operating systems and databases, the NAS software engine manages data and distributes the data over Ethernet wires
to users, servers and databases.
Storage infrastructure (switch) vendors are challenged with the convergence of SAN and NAS. Users want a
virtualized storage repository where they can view and manage all storage assets from one place regardless of
technology implementation (NAS or SAN), physical location, or vendor brand.
The Stratix GX device family integrates high-speed data transmission and programmable logic for storage switches
and storage systems. Built on Alteras new Stratix architecture, Stratix GX devices are available with up to
20 transceiver channels capable of operating at up to 3.2 gigabits per second (Gbps) per channel (3.2-Gbps
performance is pending silicon characterization). The Stratix GX solution provides system designers with flexibility,
performance, integration, and low power that are not available in any other solution.
System Overview
Storage systems contain hard disk drives, redundant arrays of independent disks (RAID) controllers and storage
shelves (see Figure 1). The tape automation system (backup libraries) duplicates data in tape-medium storage
systems. These libraries have many tape drives and can accommodate hundreds of tape cartridges. Director core
switches are high-port-count (between 64 to 512 ports) switches that control the data flow to and from the main data
centers. Director core switches offer features such as redundant power supplies, processor boards and multi-path
connections to eliminate any single point of failure. Altera Corporation
Stratix GX in Storage Applications White Paper
2
Figure 1. Storage Networking System Overview
Director core switches contain multiple cards plugged into a backplane. The cards are either port (line) cards,
processor cards, or virtualization cards. The switch fabric routes the signals to other cards plugged into the system.
Some chassis have cards that plug in at the front and in the back of the box. In this case, a mid-plane is used to route
the signals to the cards in the box. The number of cards varies from vendor to vendor.
Using Stratix GX in Storage Switches
The port modules (line cards) in storage switches support multiple ports. These are typically Fibre Channel ports for
Fibre Channel switches or Ethernet ports for NAS or IP storage switches. The following figures illustrate how
Stratix GX devices can be implemented on typical port module cards for Fibre Channel and multi-protocol switch
cards.
Fibre Channel Port Card
Fibre Channel is a data transfer interface technology that maps several common transport protocols, including
Internet protocol (IP) and SCSI, allowing it to merge high-speed I/O and networking functionality in a single
connectivity technology. The Fibre Channel standard operates at up to 10 Gbps.
The basic data flow on a Fibre Channel port card is shown in the functional blocks of Figure 2. GigaBit Interface
Converters (GBICs) convert optical data to electrical data at the line interface. GBICs pass the data on to devices that
handle FC-0 through FC-2 layer functionality such as encoding/decoding, framing, flow control, service classes,
traffic management, and queue/buffer management. Current systems use a combination of ASICs, ASSPs, and
FPGAs to handle these data path functions. Since Fibre Channel is an evolving protocol, the design platform must be
flexible to accommodate any changes. FPGAs offer the flexibility required for a Fibre Channel solution. FPGAs also
allow you to differentiate your storage equipment from competitors and allow you to go beyond the protocol
specification.
Edge Fabric
Switch
Storage Data
Center
Departmental
Storage System
Tape Automation
System
Director Core Switch
ï Fiber Channel
ï iSCSI
ï Infiniband
Remote Storage
Gateway
Remote Storage
System Altera Corporation
Stratix GX in Storage Applications White Paper
3
Designers can use Stratix GX devices for the backplane interface and traffic management functions in the Fibre
Channel storage line card shown in Figure 2. Stratix GX devices can also support the Fibre Channel physical
interface, PMA (FC-0) and transmission protocol, PCS (FC-1) for a single or multi-port Fibre Channel line card.
Figure 2. Fibre Channel Storage Line Card
Current designs use FPGAs in the data path for processing Fibre Channel frames. This involves framing, flow
control, and queue and buffer management. You can implement framing and signaling protocol (FC-2) in Stratix
devices.
iSCSI Port Card
An iSCSI port card functions similarly to line cards in the networking / access space. Therefore, PHYs and MACs are
layer 1 and 2 functions and TCP/IP stack processing, IPSec, IP packet processing, traffic management, and queue/
buffer management are layer 3 and 4 functions.
You can use Stratix GX devices for the backplane interface and traffic management in the iSCSI port card (see
Figure 3). Stratix GX devices can also support the physical layer (layer 1) electrical requirements for connection to
the communications media, encoding/decoding, clock recovery, and data transmission and reception. Stratix GX
devices can also implement layer 2 functions. You can implement the layer 3 (network) and layer 4 (transport)
functions in Stratix devices.
FC-0/1
PHY
Encoding
Link Control
O/E
O/E
FC-2
Framing
Flow Control
Class of Service
FC-0/1
PHY
Encoding
Link Control
FC-2
Framing
Flow Control
Class of Service
Traffic
Management
&
Backplane
Interface
Arbitration
SDRAM
DRAM
Controller
SDRAM
DRAM
CAM
Host
Processor
Multiple Ports
1G/2G/10G 4
Copyright © 2002 Altera Corporation. All rights reserved. Altera, The Programmable Solutions Company, the stylized Altera logo, specific
device designations, and all other words and logos that are identified as trademarks and/or service marks are, unless noted otherwise, the
trademarks and service marks of Altera Corporation in the U.S. and other countries.* All other product or service names are the property of
their respective holders. Altera products are protected under numerous U.S. and foreign patents and pending applications, maskwork rights,
and copyrights. Altera warrants performance of its semiconductor products to current specifications in accordance with Altera's standard
warranty, but reserves the right to make changes to any products and services at any time without notice. Altera assumes no responsibility or
liability arising out of the application or use of any information, product, or service described herein except as expressly agreed to in writing
by Altera Corporation. Altera customers are advised to obtain the latest version of device specifications before relying on any published
information and before placing orders for products or services.
®
101 Innovation Drive
San Jose, CA 95134
(408) 544-7000
http://www.altera.com
Altera Corporation
Stratix GX in Storage Applications White Paper
Figure 3. iSCSI Port Card
Notes to Figure 3:
(1)
Layers 3 and 4: Ipv4/Ipv6/TCP IPSec Packet Forwarding
(2)
TCP/IP Offload: link established/teardown, data transmission/reception, error handling, session timers
Conclusion
Stratix GX devices were designed to combine high performance programmable logic with high-speed transceiver
interface capabilities. Stratix GX offers up to 20 full duplex 3.2-Gbps transceiver channels (3.2-Gbps performance is
pending silicon characterization). In addition, high-speed chip-to-chip interfaces are supported through 1-Gbps
source-synchronous channels with dynamic phase alignment (DPA). Stratix GX offers the flexibility, time-to-market,
low power, and customizable solutions for high-speed storage switch applications.
Layers 1/2
PHY
MAC
O/E
Layers 3/4
1
TCP/IP Offload
2
Memory
Processor
Memory
Processor
RapidIO, HyperTransport Technology, or PCI-X Interface
Multiple