Storage Area Networks For Dummies®, 2nd Edition
Table of Contents
Introduction
About This Book
Foolish Assumptions
Conventions Used in This Book
How This Book Is Organized
Icons Used in This Book
Part I: SAN 101
Chapter 1: The Storage Area Network
Defining a SAN
Fiber versus Fibre
How a SAN Makes Computing Different
Understanding the Benefits of a SAN
Finding Out Whether a SAN Is Right for You
Who should use a SAN?
Who should not use a SAN?
Dissecting a SAN (The Four Ps)
The Parts of a SAN
The host layer
The fabric layer
The storage layer
Storage arrays
The SAN Protocols
The SAN Players
The SAN Platforms
Applications that benefit from a SAN
Applications that require a SAN
Chapter 2: SAN Building Blocks
SAN Components and How They’re Used
The Host Layer
Host bus adapters
Gigabit gadgets: GBICs and GLMs
The Fabric Layer
Understanding storage fabrics
SAN hubs
SAN switches
Data routers
Cables
Cable-connector types
SAN ports and port naming
Basic SAN port modes of operation
Protocols used in a Fibre Channel SAN
The Storage Layer
Storage arrays: Storing your data
Explaining Redundant Array of Inexpensive Disks (RAID)
RAID benefits
RAID types
Logical Unit Numbers (LUNs)
Understanding storage-array classification
Modular versus monolithic
Monolithic (Enterprise)
Modular (Departmental)
Why Cache memory makes a difference
Chapter 3: What Makes a SAN Go
Networking Basics
Moving Data at the Speed of Light
Bandwidth
Fibre Channel Protocols
The arbitrated loop
Loop addressing
The Switched Fabric
The fabric protocol
Fabric addressing
Chapter 4: What Makes a SAN Stop
Discovering What Causes SAN Problems
Preventing Poor SAN Design
Bandwidth
Too much distance between components
Excess latency
Congestion
Over-subscription
Using the Right Cables in the Right Way
Avoiding connection issues
Macro- and micro-bends, and the patch panel pain
Cable labeling
Choosing the right host bus adapter for your computer
Going with a single vendor
Mixing switch vendors
Part II: Designing and Building a SAN
Chapter 5: Designing the SAN
Basic SAN Designs: Understanding the Layers
Point-to-Point Topology
Arbitrated Loop Topology
Cascading hubs
Loop of hubs
Creating resilient hub networks
Fault-tolerant loops
Switched Fabric Topology
Types of SAN switches
Choosing which switches to use
Using the right bandwidth for the job
Trunking and what it’s used for
Basic Fabric Topologies
Dual switches, the SAN fabric building block
Loop-of-switches topology
Meshed fabric topology
Star topology
Core-edge topology
Understanding Zoning
The parts of a zone
Types of zoning
Zone alias names
Initial Switch Setup
Setting up a Brocade switch
Setting up an original McData (Brocade) director switch
Best Practices — Tips from the Trenches
When to choose a director-class switch
Standardize on a single vendor’s switches
Standardize your firmware versions
Standardize your HBA drivers
Use unique zone alias names
Using storage from multiple vendors
Always use two fabrics
Chapter 6: SANs and Disaster Recovery
How Much Downtime Can You Afford?
Gathering the data for a disaster-recovery plan
Create a detailed plan that meets your requirements
Recognizing the Importance of Distance, Bandwidth, and Latency
Distance
Bandwidth
Latency
Choosing the Recovery Site
Existing facility
Co-location facility
Choosing Where to Run the Data Replication Process
Host-based data replication solutions
Appliance-based data replication solutions
Array-based data replication solution
Shipping tapes as a solution
The Importance of Testing
Chapter 7: Putting It All Together
Building a SAN by Hand
The SAN Plan
Fabric Zoning 101
LUN security
Setting Up the SAN
Keeping good notes
Setting up the switches
Preparing the Servers
Loading the driver
Customizing the HBA card’s configuration
Planning the HBA connections
Configuring the Array
The hardware
RAID setup
Plugging Things In
Configuring the Zones
Mapping the zones first
I’m zoning out . . .
Back to the Servers: Did It Work?
Unix servers
Windows system
iSCSI, You SCSI, We All SCSI
Initiators and targets
IQN: iSCSI qualified name
SCSI Name Service
Data domains
Getting started with iSCSI
Getting serious with iSCSI
Data Migration
Network migration
Backup/restore migration
Disk-to-SAN migration
Part III: Using Advanced SAN Features
Chapter 8: Networking SANs
Defining a SAN Island
Connecting SAN Islands
Disk/data sharing
Data copying
The Storage WAN, MAN, and SWAN
Using the network only for storage management
The storage SWAN
Choosing and Using SAN Extenders
Choosing the Correct Link for the Job
IP connections
OC-type connections
Reducing Costs with Compression, Data De-duplication and WAN Tuners
Compression
De-duplication
WAN tuners
SAN Connection Protocols
FCIP: The SAN tunnel
iFCP: The SAN gateway
Stretching the SAN (The Rubber-Band Approach)
Using Connected SAN Islands (The Two-Rubber-Bands Approach)
Using a SAN as Network Attached Storage
iSCSI: An Alternative Method
Chapter 9: SAN-Based Backup
Understanding Backup
Understanding SAN Backup
The backup window
Tape drives
Tape libraries
Backup policy
Choosing a Backup Solution
Integrated tape drive in each server
Backup over a corporate LAN to a tape drive connected to an independent backup server
Backup over corporate network to robotic tape library connected to an independent backup server
LAN-less backup to shared tape library over SAN
Serverless backup to shared tape library through SAN
Disk-to-disk backup
Image copy and snapshots in the SAN
SAN data replication/remote backup
Determining How Long a Backup Will Take
Determining backup speeds
The formula for backup
Chapter 10: Mirror, Mirror: Point-in-Time Copies
The Uses of Point-in-Time Technology
Make backups
Make corruption-recovery images
Save space
The possibilities are endless
Complete versus Metadata Copies
Which PiT Type Should You Use?
Creating a PiT Copy
Managing Your Point-in-Time Copies
Pair up your volumes
Create the pairs
Splitting the mirror, snapping a copy
Doing a resync: Refresh and restore
I need my data now!
Using a PiT copy
The Finer Points of PiT
Guideline #1: Understand when to snap a copy
Guideline #2: Keep your PiT pairs separated
Guideline #3: Use the right disk storage for PiT copies
Questions to ask your SAN vendors
Part IV: SAN Management and Troubleshooting
Chapter 11: Approaches to SAN Management
Management: From Simple Networking to SANs
SAN Management from the Ground Up
Start small; think big
Documentation is key
Cable Management: Spaghetti, Anyone?
Physical cable management
Logical cable management
Labeling Your Cables
Data center coordinate system
Standard naming convention
Documenting the cable arrangements
Using a SAN Management Framework
Working with SAN management software
Communicating in a common language
Speaking the language yourself
Putting everything together
What SAN Management Gives You
A bird’s-eye view of your network
Agent-based management
Health monitoring
Records of events
Change management
Predictions of problems
Streamlining SAN Administration
Step-by-step administration
Using a framework
Automating Your System: “SAN? Do You Read Me, SAN?”
Backing up
Managing database storage
Providing a Service Level Agreement
Simple versus complex SLAs
Setting service levels
Building a Storage Management Team
SAN architects
SAN engineers
Monitoring team
SLA and performance specialists
Provisioning staff
Planning for the future
Common responsibilities
Chapter 12: Troubleshooting SANs
The Best Method: Prevention
Troubleshooting Methodology
Go with what you know
Elementary, my dear Watson
Didn’t read the manual, did you?
Build a golden configuration
Typical Problem Types
Obvious problems
Phantom problems
Continuous problems
Catastrophic problems
Example Scenarios
Scenario #1
Scenario #2
Scenario #3
Part V: Understanding the Cool Stuff
Chapter 13: Using Data De-Duplication to Lighten the Load
Understanding Data De-Duplication
Benefits of data de-duplication
How de-duplication works
Data De-Duplication in the Datacenter
The de-duplication vendors
How data gets de-duplicated
In-band versus out-of-band data de-duplication
Using Data De-Duplication in a SAN
Files: Honey, I shrunk the files
Blocks: Been there, stored that
What about hash collisions?
Why Data De-Duplication Is Important
When to Use Data De-Dupe (And When Not To)
Applications for which data de-duplication makes sense
Applications for which data de-duplication doesn’t make sense
De-Duplication in Action
Chapter 14: Continuous Data Protection
Understanding What Continuous Data Protection Is
How CDP Makes Storage Work Like a Database
CDP data journaling
Splitting the writes
CDP makes everything different
Sizing a CDP journal
Best Practices for Storage When Configuring CDP Solutions
The Truth about Near CDP and True CDP Solutions
Example 1: Recovering a database with traditional backup
Example 2: Recovering a database from a snapshot
Example 3: Recovering a database using near CDP
Example 4: Recovering a database using true CDP
CDP versus Snapshots
Using CDP to Eliminate Backups
Using CDP to Simplify Recovery and Reduce Costs
Knowing Your CDP Vendor
Chapter 15: Everything You Ever Wanted to Know about Virtualization
Understanding What Virtualization Is
Exploring the Types of Virtualization
Implementing Virtualization in a Datacenter
Server virtualization
Storage virtualization
In-Band versus Out-of-Band Virtualization
In-band virtualization
Out-of-band virtualization
The Virtualization Vendors and Where They Play
Host-based storage virtualization vendors
Fabric-based virtualization storage vendors
Storage-array-based virtualization
Part VI: The Part of Tens
Chapter 16: Ten Reasons to Use a SAN
You Want Better Disk Utilization
You Need a Good Disaster Recovery Solution for Multiple Applications
You Need Better Availability for Your Applications
You Need More Storage Room
Backup Is Taking Too Long
You’re Focusing on Server and Storage Consolidation
You’ve Been Tasked to Save Your Company Money
You Need to Manage Storage for Many Locations from a Central Site
You Need to Decrease IT Management Costs
You Need Better Performance for Your Applications
Chapter 17: Ten Reasons NOT to Use a SAN
You Need Larger File Servers
You Only Have a Few Inexpensive Servers
You Want to Save Your Company Money This Year
You Want to Use the Latest and Greatest Solutions Available
You Need a Disaster-Recovery Solution for a Single Application
You Want a SAN but Don’t Have the Budget
You Use Gigabit Ethernet on Your LAN
Everything Already Runs Fine
You Need to Back Up Multiple Remote Offices over Slow Links
You Need to Replicate Your Data for Disaster Recovery but Can’t Afford Fast WAN Connections
Storage Area Networks For Dummies®, 2nd Edition
Christopher Poelker
and
Alex Nikitin
Storage Area Networks For Dummies®, 2nd Edition
Published by
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Copyright © 2009 by Wiley Publishing, Inc., Indianapolis, Indiana
Published simultaneously in Canada
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About the Authors
Christopher Poelker has been in the field of computer technology since 1974. Chris was an electronics engineer in the U.S. Army, and tried to stay out of trouble by hiding in tanks while installing laser range finders and computer-aided ballistic trajectory systems. After leaving the service, Chris went to school in New York City at good old Control Data Institute and was hired as a field engineer by Digital Equipment Corporation. In his spare time, Chris started his own software company, developed databases, and became a Microsoft MCSE and instructor. Chris worked for Digital for 18 years until it was bought by Compaq, where he stayed on as a StorageWorks systems engineer until joining Sun Microsystems in 2000. Chris left Sun to become a consulting storage architect for Hitachi Data Systems and became the district storage manager for HDS in New York City. In 2006, Chris left HDS for FalconStor software, where he now works as the Vice President of Enterprise Solutions. Chris has designed and implemented storage networks for many of the Fortune 100 companies in the U.S. and around the world. In his spare time, Chris sometimes speaks at industry forums, writes magazine articles, and has acted as the SAN expert at SearchStorage.com.
Alex Nikitin, currently a systems expert at HBO, has logged in 15 years in the Information Technology industry. Alex has worn many hats in this industry, ranging from application programmer and network administrator to the ultimate responsibility over large server farms, and storage and backup solutions for some of the world’s top financial and pharmaceutical companies. Alex and Chris worked together at Hitachi Data Systems in New York, where Alex was the “go to” guy for difficult storage designs and implementations. Prior to joining HDS, he also spent time growing the install base of Storage Area Networks as a Professional Services Consultant for EMC Corporation, implementing SAN solutions for various companies, large and small, on Windows NT/2000, Solaris, HP/UX, AIX, and Linux platforms. Seemingly always cast in a storage-centric capacity, his career has focused on caring for and reliably delivering vast amounts of storage to his user community.
Dedication
Christopher Poelker: To my sister Nancy, whose love and friendship meant the world to me.
Author’s Acknowledgments
Christopher Poelker: I would have never been given the chance to write this book if it weren’t for my friends at TechTarget, who used to run the SearchStorage.com Web site: Michelle Hope and Maryann Tripp. These two wonderful women were the reason I was introduced to Melody Layne and Susan Christophersen of Wiley Publishing, who made the first book possible, along with Teresa Artman, who spent many a long night copy-editing the manuscript and making up for my horrible writing skills. (I should have paid closer attention during eighth-grade English!) For this second edition, I would like to thank Kyle Looper and Kim Darosett for their patience during deadlines when my day job was getting in the way of keeping this edition on track.
I’d also like to thank my partner in crime and co-author, Alex Nikitin, who again saved my marriage and my duty as a father to my children by taking over some of the load and helping me crank out some of these chapters. Alex is one of the best storage guys I have ever had the privilege of working with.
Thanks also need to go this time to FalconStor software, for letting me proceed with this project and letting me play hooky now and then to crank out a chapter or two. Thanks to ReiJane Huai, Wendy Petty, Wayne Lam, Alan Chen, Tom Strumpf, Bruce Sasson, Joanne Ferrara, and everyone else at FalconStor who filled in or helped me out to give me time during the writing of this book.
Special thanks to all the folks who taught me most of the things I know about storage: my brothers, Lenny Poelker and Greg Poelker, who are a heck of a lot smarter than I! Also to my mentors: Wayne Lam, Wai Lam, Stanley Qin, Irving Moy, David Shyu, Cartic Vengkatraman, Gene Chesser, Steve Sicola, Paul Kruschwitz, Jimmy Wu, Raymond Tong, Paul Mitchell, Mike Mendola, Jo McCausland, John Lallier, Nick Sinish, Brian Rice, Steve O’Rielly, Catherine Brown, Frank Cizin, Leonard Hayward, Charlie Mulrooney, Paul Poon, Don Thatcher, Tony Merschdoff, Jeff Sinisgalli, John Fonseca, Marty Citron, Al Catalano, Tom Lindemann, Roland Song, Pierre Dansereau, Mike Pierro, and most of all, Kevin Shumacker, whose help over the years I could never repay. Thanks to Ken Garnau, Nancy Berliner, and Charlie Santana for help with the mainframe stuff, and everyone I ever met from Brocade/McData, and Emulex.
Tom Clark and Robert Stout, Nancy Jennings, and John Dorl from the original Nishan systems were a big help with helping me figure out SAN extensions, (especially Tom’s books!), and Mark Farley’s book was the first I read on SAN and still is one of the best. (I guess I learned things the hard way, by just doing it.)
Finally, thanks for the support of my family: Deborah, my wife, for being a single mother again while I was writing the book, and of course, my children Cole, Chris, and Rachel for all their support and being the wonderful people they turned out to be.
Publisher’s Acknowledgments
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Introduction
Welcome to Storage Area Networks For Dummies, 2nd Edition! The first edition was the book we wish was around when we were trying to learn about this stuff! We tried to take a fairly mundane topic and make it a fun read so you could get up to speed on storage networking as quickly and painlessly as possible. This second edition is written in the same spirit as the first.
When the first edition was written in 2003, very few books on storage area networks (SANs) were available. The books that were available were very narrow and extremely technical in focus. They were about as fun to read as the directions for setting up a DVD player. Although more books about storage networking are available now, most are still very technical and about as fun to read as the U.S. tax code (nothing against accountants here!).
Over the years, this book has become the standard bearer in keeping the subject concise, simple, and fun, and has now been updated to include all the new cool stuff and changes that have occurred since the original printing. Let’s face it — most folks typically look for a fast and easy way to get information; you want the information you need to know, and not everything there is to know, so this second edition uses that same point of view common to all of us poor slobs who need to make a SAN work with no budget, no training, and no time. So don’t worry, be happy — and just have some fun!
About This Book
The mission of this book is to help you find your way around while exploring the topic of storage area networking. The book is dedicated to individuals who, for better or for worse, have been tasked with designing, implementing, configuring, or troubleshooting a storage area network. We hope that the information here will enable both the beginner and the moderately expert storage professional sort through the ins and outs of a SAN. We use familiar language to demystify the technology and translate the jargon as necessary. You’ll discover how to choose the right hardware for the job, design a SAN by using the best practices in the industry, connect everything to make it work, and troubleshoot the SAN to fix problems when they occur.
You also get to delve into the hard stuff — the stuff that many companies pay expensive consultants for (who have usually just read a book like this just before they were hired!), so be brave, and we’ll do our best to make this painless. If you want to understand what a SAN is and what it does, you’ve come to the right place. Everything you should need (or want) to know about storage area networks is here in one location.
Foolish Assumptions
We have one or two foolish assumptions about you, the reader of this book:
You are responsible for or have worked with computer storage before.
You might want to continue working in that field of endeavor.
You want to find an easy way out of your networking storage problems so you can get home and play video games, watch TV, and drink beer with your friends.
We also assume that you don’t want to become an instant expert. You want to know just enough to be able to speak intelligently on the subject matter but also know when it’s time to call in an expert.
This book tries to you get past all the little details that get in the way of understanding a subject by using a real-world approach. We didn’t create the technology; we just know how to make it work because we’ve been in the field for more years than we care to say. This book tries to impart just enough good info to help you make your stuff work — and to understand enough to know when someone is misleading you or trying to rip you off. The best defense is a good offense.
Conventions Used in This Book
We want you to understand all the instructions in this book, and in that spirit, we’ve adopted a few conventions.
When you hit a chapter in which we ask you to do something, you will be prompted by a numbered list. The numbers in the list are the order of the steps that you need to take to accomplish the task at hand. Just follow the steps listed, and everything should be just fine. If you need to enter something on the keyboard, we ask you to type it. If you need to use your mouse, we ask you to click it. That’s all there is to it.
How This Book Is Organized
This book is designed as a reference, so you don’t have to read the book cover to cover. Just look in the Table of Contents to find the topic you’re interested in and start reading. If you’re unsure of some of the acronyms you’ve been hearing out there, check out the Cheat Sheet at the front of this book for easy reference.
The book is organized in seven parts.
Part I: SAN 101: This part covers the basics of storage area networks, including what you need to know if you’re going to buy a SAN, build one yourself, or have someone build it for you.
Part II: Designing and Building a SAN: This part of the book handles all the fun stuff, such as how to add more storage to your servers and how to connect everything and get it running. It also covers what you need to know if you already have a SAN in place or need to know how to use it or set it up properly.
Part III: Using Advanced SAN Features: If you’ve always wanted to know what the heck a snapshot copy was, this is the place to find out. This part also covers advanced topics such as backing up your data, which will help you get more bang for your buck out of your SAN.
Part IV: SAN Management and Troubleshooting: Every now and then, something goes bump in the night. This part shows you how to manage and troubleshoot problems when they occur as well as how to avoid having to face those problems in the first place.
Part V: Understanding the Cool Stuff: This part covers the cool new advances in storage area networking since 2003, such as storage virtualization, data de-duplication, and advances in data protection and replication such as Continuous Data Protection (CDP). You find out how to use these technologies to help you save money and become more productive and better prepared when trouble happens.
Part VI: The Part of Tens: This part includes ten reasons to use a SAN and ten reasons not to.
We’ve also provided a bonus chapter titled “Outsourcing SAN Solutions” that you can download from the book’s companion Web site at www.dummies.com/go/sanfd2e.
Icons Used in This Book
To help you get the most out of this book, we’ve placed icons here and there. Here’s what the icons mean:
Next to the Tip icon, you can find shortcuts and tricks of the trade to make you more productive without even realizing it.
Where you see the Warning icon, tread softly and carefully. It means that we’ve been burned by this already and don’t want you to have to learn the hard way, as we did.
Stuff marked with the Remember icon is like jotting a note to yourself in a class. Make an effort to bend the ear of the page so that you don’t forget it.
Okay, we probably put too many of these icons in the book. But what the heck . . . sometimes trying to explain this stuff is like writing a book on Brain Surgery For Dummies. We need to point out the details at times so you don’t end up with a migraine.
Part I
SAN 101
In this part . . .
The computer industry is funny. As soon as you get comfortable with the latest technology and become the resident expert, something new comes out, and the whole learning process starts all over again. Some people enjoy the challenge of learning about something new, and some think it just makes life more difficult. This first part of the book tries to make things easier by introducing you to storage area networks, or SANs. Just like in high school shop class, when you were introduced to the drill press, the table saw, and the first aid stations, we introduce you to the various tools that you use to build a SAN. We tell you what each tool does, why it’s necessary, and how you can use it in your new SAN project.