Geographically Dispersed Clustering with Clariion

Thanks to Ira Pfeifer for jump starting this topic…I would’ve hit this subject eventually as this has been a rather frustrating experience that I’ve gone through over the years. One of the things that I’ve been pushing for many, many years at EMC is to develop a “GeoSpan” equivalent product for the Clariion environment. In my opinion, our main target audience for CX arrays is the Windows server environments so it seemed like a logical progression for the GeoSpan product to release a similar product for the Clariion line. Symmetrix has SRDF, Clariion has MirrorView. Seemed like a no-brainer to me.

The first sign that this was NEVER going to happen was the name change from GeoSpan to SRDF/CE…SRDF = SYMMETRIX Remote Data Facility so it would’ve been silly to name a product “SRDF anything” if we had plans to incorporate the CX arrays. Next sign was the level of resistance from product management. The PMs kept ignoring my pleas and finally, they asked that I provide a business case scenario showing the market for such a product…this was management’s way of politely telling me to go away. They were fully aware that I was a technical resource and it would be unlikely for someone like myself to provide the necessary logistical information to pursue this further.

Unfortunately for them, I actually do have the vision and desire to see such a thing through and could not be swatted down by some menial paperwork. I found a dozen different customers that have requested exactly this type of product and I submitted a pretty decent case to the different product groups. This got some attention and the developers from the MirrorView team were engaged by the SRDF/CE team to research the feasibility for such a software product. The outcome was that the MirrorView APIs were not capable of handling the types of commands necessary for a GeoSpan equivalent product and it would require a total rework of the MirrorView coding to make this functional. In the end, this idea was rejected even though this is really something we should be providing to our customers.

With that said, it is still possible to setup a geographically dispersed cluster using Clariion with MirrorView with Windows 2003. One of the main reasons why we were told that MV/CE (my name for the SRDF/CE equivelant for MirrorView) couldn’t be done was that MV couldn’t handle the quorum arbitration needed to support a geocluster. If you use a MNS quorum, there’s no need for MV to get involved with the quorum arbitration. You could build a MNS cluster and then create a generic script or application resource to control the MirrorView failover. You would create your physical disk resources and make then depend upon these generic app/script resources and voila…you now have a geographically dispersed MirrorView cluster. If you’re not familiar with NaviCLI commands, I’ve been told that you could contact EMC professional services to help you develop these scripts…some customers are actually doing this today in their environment. 

I spent a little bit of time trying this last week and I successfully setup this type of configuration in my lab environment so I know that this is possible. Now whether or not such a thing would be supported…from an EMC perspective, you would need to submit an RPQ for support from EMC. For MSFT support, this would need to pass HCT testing and submit it to MSFT for review. I do not think there are currently and MirrorView clusters in the Windows Catalog yet.

Another possibility for the Clariion environment would be to use NSI’s GeoCluster or DoubleTake to create host-based mirrors over IP. This is something I plan on testing myself in the next couple of weeks. Stay tuned for those updates.


Let me first discuss my pet project, SRDF/CE for MSCS. What is SRDF/CE you ask? Well it is EMC’s geographically dispersed clustering software. SRDF/CE is an EMC proprietary product that is used to integrate EMC’s SRDF technology with MSCS. Basically, it is the glue that combines HA from MSCS with the DR capabilities of SRDF remote mirroring to form a true geographic clustering solution. Upon failover, SRDF/CE issues the necessary SYMCLI commands to automatically RW enable the devices at the DR site then allowing the disks to come online at the DR location. This provides a fully automated DR solution with high availability.


It’s entirely possible that you work for a company that owns EMC hardware and you’re not aware of this little product. I’d love to hear from you if this is true. For some unknown reason, the marketing folks at EMC have never given this product any respect so it wouldn’t surprise me at all that you haven’t heard of this. One clear example would be to take a look at the EMC web site and attempt to find some information about this product. There used to be a good amount of info available for GeoSpan, but since the product “evolved” into SRDF/CE, the marketing has shifted away from the product. It really is upsetting to have spent so much time working on a project and then see that your company does not support the work that you’ve done. Am I bitter? I suppose so. I honestly don’t know how this product has survived and grown in popularity over the years.


SRDF/CE was originally called GeoSpan for MSCS. Many moons ago, the company decided to change the name to align with other product naming conventions and this became SRDF/Cluster Enabler…rolls off the tongue, doesn’t it? Anyway, some good and some bad came with this name change. The good was that we added some wizards to help with the install. The GeoSpan install was a nightmare and practically could never be installed properly without the assistance of someone that had previously installed the product. Also, we got rid of some of the ugliness of GeoSpan which really wasn’t a GUI. We made the SRDF/CE GUI a MMC snap-in so it was now certainly a GUI product. The bad…well, we added some additional checking which caused big performance issues on the RDF links. This is one issue that still plagues us today and has left a bad impression at a few customer sites. Other bad news, we added some instability to a product that is supposed to be used in a HA environment. Early versions of SRDF/CE were infamous for causing database corruption which triggered unnecessary failures in a cluster environment.


Over the past couple of years, SRDF/CE has significantly improved its stability and performance. We still need to tweak the registry and some other software settings to get the RDF link performance just right, but we’re definitely releasing a better product these days.


A few years ago, someone (I think it was a customer) asked me if I would use SRDF/CE in my environment if I were an EMC customer. I had to think really hard about this one since I work in a support center and really only see the bad side of our products…believe it or not, customers never call in to tell us how well things are running. J My answer at that time was something like since I knew the ins and outs of the product, I would’ve been comfortable implementing this in my own environment. I don’t know if that’s very comforting endorsement, but it was the truth.


Today, I really do enjoy the SRDF/CE product and would easily recommend implementing this into any customer’s site…including my own were I an EMC customer. The newer versions (versions 2.1 or higher) have really made significant improvements over the first couple of releases and continue to evolve for the better.


Welcome to my blog!

I’ve finally decided that it’s time to start a blog. Why? Well, it wasn’t only a bandwagon thing…I thought that this might help to keep me motivated to do some of the things that I’ve been intending on doing for many, many moons. I hope that if I put these plans in print, it might actually help force me to complete some if not all of these goals…and also I want to be cool like Rod and Russ <g>


About me


The main focus in my work life for the past seven years has been geographically dispersed clustering at EMC. So far, I have focused on the GeoSpan and SRDF/CE for MSCS products. I’m hoping to expand my horizons a bit and try some others products and compare and contrast the technologies.


I’ve worked at EMC Corporation since 1999. My main focus at EMC has revolved around their software products for Microsoft operating systems. I started as a “New Product Analyst” where my job was basically to learn the new products and then police the release of the product and fill in the gaps as necessary. One of those new products was a little gem called GeoSpan for MSCS. Little did I know that this would be a life altering project that I would never truly escape. It was the only project I was assigned to at the time so I spent ALL of my time testing this product.


I had never worked with Microsoft clusters before so this was totally new ground for me. I worked with our SVT guy, George, for months installing and testing the code. We tried every possible scenario with the available hardware we had and found many different issues with the code. We delayed the release of the product for over six months because of the issues that George and I uncovered. By the time the product was released, I was truly an expert with this software and knew every little detail (minus the coding).


Since I was now one of two non-engineering GeoSpan experts in the company, I was called on frequently for assistance with implementations at customer sites across the globe. It was because of this field experience that I really became known as a God of GeoSpan. As popularity increased, I was also called upon to deliver training sessions around the world to internals as well as customers.


As new versions were released, I would again test, implement and teach the new versions. Today, I am still constantly asked to help teach and implement, though my job officially is to support the product. I suffered some burnout from all the traveling and I switched into a tech support role so I wouldn’t have to travel as much. The travel has slowed, though I am still occasionally teaching.


During my downtime, I spend a lot of time in the Usenet newsgroups related to clustering. I read the questions posted on the newsgroups and would do a little research to come up with answers. I always found it amazing that people would be wise enough to use newsgroups to seek out assistance, but didn’t have enough common sense to search Microsoft’s knowledgebase for the answers. I always made a point to include a link to the KB in my posts so they might take the hint. Anyway, I found it fun to help out people and I admit that I would also do some self-promotion of “my” products. I try to keep an open mind and not be too biased, but I can’t help myself at times.


Anyway, I spent a few years helping out in the newsgroups and one day I got an email announcing that I had been nominated as a Microsoft MVP. I was awarded the MVP for Windows Server – Clustering on Jan 1st, 2004. I’ve been re-awarded each year since because of my work in the newsgroups. I truly do not feel worthy of this award, but who am I to turn down a free gift from Bill Gates J


To this day, I don’t know how I was nominated or who nominated me, but I do really appreciate it. Seeing the work done by my fellow MVPs is a great way to keep motivated and makes me want to do more for the community.




Some of the things I’d like to begin working on are the following:


         I’d like to start my own website dedicated to geographically dispersed clusters. I’m not sure how much different this will be compared to this blog so for starters, I’ll just blog about it and see where this leads

         I’d like to test and become more versed in other geo-cluster products. I’d eventually like to compare and contrast the strengths and weaknesses of each solution.

         I’m very interested in testing the new geographic capabilities of SQL and Exchange.

         I have every intention on testing Longhorn beta 3 (when released). I’m very excited about the new features coming for LH and of course I haven’t had the time to even consider looking at it yet.

         I’ve also been considering writing a book about geographic clusters, but figured I needed to broaden my horizons first. Also, after reading about the horrors that Russ has gone through, maybe I’ll just stick to blogging