In 2004 I bought the 1st Edition Storage Area Networks for Dummies (now in its 2nd Edition) and read 100 pages or so, life got in the way, and now 2011 I’ve decide to finish it. I know what you’re thinking, “Why read a Dummies book?” Back in the day this book had the information I was looking for and it helped me on my first virtualization design. In today’s world some of the information is somewhat outdated however it still has a lot of the basic SAN fundamentals and concepts of today’s SAN’s.
An Easy Read and my own personal Dummies Tip…
Going through the book I kept in mind this is a dummies book and it’s meant to be an easy read. This book was an easy read and it was a great refresh on SAN technologies. There was quite a bit of outdated material in this book (I expected this) and it was interesting to see how technology had progressed since 2003 days. Example – In 2003 FCoIP was referred as FCIP or iFCP. The basic book layout comprises of 5 different parts ranging from SAN 101 through Management & Configuration. One thing I dislike about technical books is when an author spells out an acronym once, never to return to it, and then references the acronym over and over. I couldn’t tell you how many times I go back to find out the meaning of an acronym. This book overcomes this issue and it does it so well it becomes unnecessary. Example, they mention FC-AL (See Cliff notes below), and talk about how FC-AL (For more information about Fibre Channel Arbitrated Loop – Please see my cliff notes under the section “Some General cliff notes below”) is an old technology. Only a fool would use FC-AL (Tip: if you’d like to know more about FC-AL see my cliff notes below). Hopefully you get my point. It was nice to have the reference but mentioning it too often (it seemed like 40 times) got a bit annoying. Here’s a Dummies Tip: Authors reading this blog – please find a happy medium, do it, and don’t blame your editor for taking it out. I mean after all it’s your book, right?
While I was reading the book we had several vendors present their products at my current employer. They mentioned a lot of the terms I listed below. So yes this books still has value and for a person who wants to learn the basics I would recommend they read the 2nd edition and then on to “higher education”. I noted lots of errors in the book especially around their math or what appeared to be simple cut/paste issues. I did go to the www.dummies.com site to see if they printed book corrections but I was unable to find it.
Some General Cliff Notes…
Fibre Channel protocol is spelled fibRE not Fiber – http://en.wikipedia.org/wiki/Fibre_Channel << My spell checker really hates fibre J
Single Mode Fiber Cable – Smaller diameter means a more direct path for the beam, usually yellow, for long distances (Up to 10K), usually uses a higher powered laser
Multi Mode Fiber Cable – Larger diameter means a less direct path for the beam, usually Orange, for shorter distances (<500M, Normal 10 to 20M), can use an LED or vertical-cavity surface-emitting lasers (VCSELs)
Common fiber connectors – LC – Most common, SC – Older Larger connector, ST – Older BNC Twist on style http://en.wikipedia.org/wiki/Fiber_connector
FC-AL – Fibre Channel Arbitrated Loop Protocol, used with a SAN hub – RARE replaced by SAN Switches, not one device can exceed the max speed, the more devices the more congestion occours, MAX of 128 devices per hub, common use might be for SAN based TAPE.
FC-SW – Fibre Channel Switched Protocol, used with a SAN Switch, more efficient then HUBS, devices can cross communicate with each other, 1000’s of devices can be connected, each device is assigned a WWN(World Wide Name)
Modular class SAN – Use Controllers which are separate from disk shelves
MonoLithic class SAN – Use disks that are assembled inside the array frame, -these disks are connected to many internal controllers through lots of cache memory
Storage Bus Architecture Array – One thing can happen on the array at a time (Like a Hub Switch)
Storage Switch Architecture Array – Multiple things can be going on at the same time with less of an impact on I/O performance.
LUN – Logical Unit Number, usually represents a RAID set represents all the smaller physical drives as one logical disk to your server.
RAID – It depends on who you ask it can mean Redundant Array of Inexpensive Disks or Redundant array of Independent Disks. Funny thing this book was pre NetApp, they mention RAID 4 is no longer in use. Oh contraire NetApp uses it!
LUNS – Logical Unit Numbers represent the storage space formed by a RAID set. It may contain the partial or entire space.
Fiber Optic Cable – When Fiber Optic cables are used within a storage network they are spelled fibre channel cables. This helps to distinguish their meaning from other fiber based cables such as telecommunications.
ISL (Inter-switch link) – the term used to describe the connection between two switches in a fabric
Fabric Protocol – A SAN fabric may include Routing and conversation between switches, Listing Services, and Security
WWN (World Wide Name) – Devices in the SAN fabric are addressed by the World Wide Name. WWN’s consists of a 16 HEX numbers which make a 64 Bit Address.
Three Layers to a SAN Design AKA the Basic SAN topology – Host, SAN, and Storage
DAS – Direct Attached Storage AKA Local Host Storage
Point to Point – Host to disk Storage via a Fibre Cable (Require dedicated Storage Ports)
Arbitrated Loop Topology – Most likely you can find these devices on ebay, they might even pay you to take them off their hands. Basic designs around FC-AL hubs are cascading, fault-tolerant loops and your basic hub loops.
Switch Fabric Topology – Most prevalent for today’s fibre networks. Switch types include smaller modular (usually single failure) and larger director class (very redundant) switches.
Basic Switch Fabric Topologies – Dual Switch, Loop of Switches, Meshed Fabric, Star, Core-Edge
Zoning – Is a method used to segregate or separate devices connected to a switch fabice via switch based security. A Zone in many ways is similar to an IP Switch VLAN. They can span multiple switches. Zoning is typically used to separate storage from different operating systems. If by chance a windows server could see all the storage it might write a signature. If this space belonged to a UNIX server this could make it unusable. Other uses could be zoning storage by QA, Test, DEV, and Production networks. Zoning can come in two forms – Soft AKA by WWN or Hard AKA by physical switch port.
It’s a good starting place for those interested in SAN technologies, this books has some value in today’s world BUT if you choose this book then I suggest you read the latest edition…
Thanks for reading my post… I’m off to read my 2nd book of 4 VMware ESX and ESXi in the Enterprise 2nd Edition by Edward Halekty