Last week, Paul Weinberg of eChannelLine.com asks Is this the year of the SAN (again)?So, I thought this week I would cover my thoughts and opinions on storage networking. We oftenfocus on servers or storage devices, and forget that the network in between is an entire worldon itself.
I believe Mr. Weinberg is basing this on the idea that in 2007, over 50 percent of disk will beattached over SAN, edging out the alternative: Direct Attached Storage (DAS). But perhaps 50 percentis the wrong number to focus on. In 2007, The United Nations estimates thatcities will surpass rural areas, with just over 50 percent of theworld's population. Does that make this the "Year of the City"? Of course not.
Instead, I prefer to use the methodology that Malcolm Gladwell uses in his book, The Tipping Point.(I have read this book and highly recommend it!)Gladwell indicates that the tipping point happens at the start of the epidemic, not when it is half over.Isn't it better to celebrate the sweet 16 debutante ball when young ladies have completed their years of training and preparation, and are ready to be introduced to the rest of the world, rather than after they are thirty-something, married with children.
Let's explore some of the history. Stuart Kendric has a nice 7-page summary on theHistory & Plumbing of SANs.
IBM announced the first SAN technology calledEnterprise Systems Connection (ESCON) way back in September 1990. This allowed multiplemainframe servers to connect to multiple storage systems over equipment called "ESCON Directors" that directedtraffic from point A to point B. Before this, mainframes sent "ChannelCommand Words" or CCWs, across parallel "bus and tag" copper cables. ESCON was serial overfiber optic wiring. SANs solved two problems: first, it reduced the "rat's nest" of cables between many serversand many storage systems, and second, it extended the distance between server and storage device.
For distributed systems running UNIX or Windows, the CCW-equivalent over parallel cables was called Small ComputerSystem Interface (SCSI). The SCSI command had over 1000 command words, so for its Advanced Technology (AT) personal computers (PC AT), IBM introduced a subset of SCSI commands called ATA (Advanced Technology Attachment). ATA drives supportedfewer commands, ran at slower speeds, and were manufactured with a less rigorous process. Today ATA drives are about 55 percent the cost per MB as comparable SCSI drives.
Anyone who has ever opened their PC and found flat ribbon cable with eight or sixteen wires in parallel, can understand that the same issues applied externally. Parallel technologies arelimited to distance and speed, as all the bits have to arrive at the end of the wire at approximately thesame time. Direct attach schemes with every server attaches directly to every storage device were also problematic.Imagine 100 servers connected to 100 storage devices, that would be 10,000 wires!
So, a new technology standard was developed, called Fibre Channel, ratified in 1994.The spelling of "Fibre" was intentionally made different than "Fiber" on purpose. "Fibre" is a protocol thatcan travel over copper or glass wires. "Fiber" represents the glass wiring itself.
Fibre Channel is amazingly versatile. For today's Linux, UNIX and Windows servers, it can carry SCSI commands, and the combination of SCSI over FC is called Fibre Channel Protocol (FCP). For the mainframe servers, it can carry CCW commands. Running CCW over Fibre Channel is called FICON. This convergence allows mainframes and distributed systems to share a common Fibre Channel network, using the same set of switches and directors.
We saw the use of SANs explode in the marketplace over the past 10 years, and then cool down with a series of mergers and acquisitions. Last year, Brocade announced it was acquiring rival McData, so we will be down to two major players, Cisco and Brocade.
So, IMHO, I think we are well past the "Year of the SAN".
Continuing my week's theme on travel, conferences, and Japan, I provide three more"survival words" in Japanese language. These might seem like an odd trio, but they comein very handy.
Continuing this week's theme on Storage Area Networks, today I thought I would talkabout the various terms we use for our equipment.
One area of confusion are the adjectives "entry-level", "midrange" and "ent If you are asking yourself "which size is right for my company?" or "is my company big enoughfor a director?" you are asking the wrong questions! Instead, determine a SAN configurationthat meets your workload, and then decide the components for that design. McData coined a phrase called "core/edge" design that is considered today as "Best Practice" throughout the industry.A good write-up can be found here at SearchStorage.com. Basically, you put your big beefy "core" directors in the center of the room, and then surround it with midrange switches, that then these connect to "edge" switches, that then connect to the servers and storage near them. As you grow, this design can easilyscale to grow with you. So, if you need help implementing a SAN for the first time, or upgrading the one you have,call IBM, we can help!
If you are asking yourself "which size is right for my company?" or "is my company big enoughfor a director?" you are asking the wrong questions! Instead, determine a SAN configurationthat meets your workload, and then decide the components for that design.
McData coined a phrase called "core/edge" design that is considered today as "Best Practice" throughout the industry.A good write-up can be found here at SearchStorage.com. Basically, you put your big beefy "core" directors in the center of the room, and then surround it with midrange switches, that then these connect to "edge" switches, that then connect to the servers and storage near them. As you grow, this design can easilyscale to grow with you.
So, if you need help implementing a SAN for the first time, or upgrading the one you have,call IBM, we can help!Read More]
Today, in the US, is Martin Luther King day. There is a good post about this by Seth Godin.Dr. King had a vision for the future, and is most remembered by his speech that began: "I have a dream..."
IBM also has a vision for the future, and like Martin Luther King's speech, is startingto enable change. Last February 2006, IBM launched "Information on Demand", a visionthat involves bringing together our hardware, software, and services.
The impact has not gone unnoticed. Barron's featured IBM in an article titled "The New IBM".
I suspect bloggers helped get the word out. Here's a graph fromYahoo! Financeshowing the IBM stock price over the pastsix months. This blog started in September, when stock was in the low 80's, and now it is in thehigh 90's. I can't take all the credit, of course, as there are now over 3000 IBMers blogging, either inside thecompany, or externally to the rest of the world.
And the future continues to look bright.Greg over at IBMeye feels thatIBM stock poised for anotherstrong year.
If the analysts are right, 2007 is going to be a good year!