Monday, January 15, 2007

Two Myths about iSCSI Adoption

… Continuation of my opinion from previous post to the expanding iSCSI debate in the storage blogosphere.

Check out opinions of Tony Asaro and Steve Duplessie on debate between Dave Hitz & Chuck Hollis. Beth Pariseau also wrote a nice summary of the debate. Chris Evans is taking on in-depth investigation of iSCSI. I am looking forward to reading about his experiments and analysis.

Since my last post, I received few emails and phone calls with skepticism, typically bestowed on me, after writing an opinion that doesn’t align with storage people with fancy titles and so-called experts. Without going into specific details, I worked with iSCSI time-to-time for over six years in variety of roles on variety of iSCSI projects.

And, if you are just starting to understand the issues with iSCSI adoption explained in Chuck’s post, you have lot to catch up.

Controversial Myths

Chuck expressed some good thoughts about the future trends and driving factors for iSCSI adoption.

In my experience, some of the driving factors may be just red herrings. These are the myths that originate from wishful thinking of people promoting iSCSI instead of realities of the iSCSI adoption impediments in customer environment.
First, I think you’ll see more of the same: iSCSI in smaller, greenfield SAN builds where FC isn’t entrenched yet. But from small acorns mighty oak trees grow.
Myth #1 The smaller greenfield iSCSI environment will grow without any challenge.

This myth is created when people take the “switching costs can outweigh any benefit of a new technology” lesson too literally. They forget that as long as a technology is not fully entrenched, it is not very difficult to get people to switch. And that is the challenge for smaller Greenfield iSCSI installs. They are not fully entrenched yet thus not difficult to switch to something else like FC.

Two key points to ponder are:
  1. Why greenfield iSCSI environment came about in the first place?

  2. What happens when these small installs are considered for expansion?
Going out a bit farther, I believe that further cost reductions in 10Gb ethernet technology will encourage people to take another look at an alternative to FC.
Myth #2 10Gb Ethernet will save the day for iSCSI.

This myth is created when people assume that major hurdle to iSCSI adoption is speed and feeds. If history is telling, a new technology doesn’t replace incumbents just because of incrementally higher performance. Either new technology has to blow the incumbents out of water with several folds increase in performance or offer a value proposition that is not present in incumbents.

Just consider this, nobody would care about data de-duplication if it was offering 2x increase over conventional compression, but a 20x increase gets everyone’s attention. From another perspective, today you will be considered underdog with a Virtual Tape Library (VTL) solution that doesn’t have de-dupe even though VTL with de-dupe is slightly slower performing due to extra de-dupe processing overhead.

Another underlying assumption of this myth is that performance of everything else connected to 10GbE will remain the same as with current 1GbE and data transfer requirements will not grow. Fat chance!

Before 10Gb Ethernet can be considered for underlying iSCSI infrastructure, it also needs to be fully entrenched in customer environment as preferred networking infrastructure technology. There are too many infrastructure and political challenges to kill any 10GbE adoption for iSCSI environment without the Ethernet owners having the first crack at it.

The above observations are based on my past experiences with few expansion projects for small iSCSI installs. One of the project even considered 10GbE. In the end, it was too easy to replace iSCSI install with FC-SAN than expand them.

Controversial Positioning

I close this post with two controversial iSCSI positioning statements that I believe are impeding it’s adoption. No explanation provided at this time and you are welcome to chime in, if you desire.

Position #1 iSCSI is a storage interconnect leveraging Ethernet.

Posiiton #2 iSCSI is a replacement for or complementary with FC.


  1. Hi Anil

    I had no idea I would stir up such furor by simply stating some rather plain observations about the state of iSCSI today.

    I, for one, try not to get too religious about technology. I may be in the minority on this one.

    I must say that my (faint) optimism around 10Gb is simply based that when 10Gb gets installed for data networking in the data center, there'll be a strong temptation to at least evaluate the same technology for storage networking.

    It's a faint hope, though.

    And you have a point about greenfield iSCSI shops growing up. At some point, they'll need to hire storage pros, and -- well -- those pros most likely will recommend FC.

    I'm afraid it may be more grim than I let on originally.

    Thanks for the posts!

  2. Chuck, thank you for the comments.

    Current iSCSI market positioning as storage interconnect leveraging Ethernet is resulting in it getting squeezed out from both ends, Ethernet and FC. Nobody who has interest in Ethernet or FC want to touch it in customer environment.

    But I still see potential for iSCSI where FC is unfit like storage interconnect for virtual machines that are mobile between hardware platforms.

    I also expect one day these small iSCSI greenfield installs may become backbone of grid storage within an organization. FC will be unfit at that point as a backbone connecting various iSCSI islands.

    Failure of iSCSI is not result of technology, speeds and feeds but of market positioning. FC strength is at hardware and fails at software level. Anytime a storage interconnect need to be mobile, i.e. implemented in software level, iSCSI can be positioned as the only choice.