The Storage Compass

I am sure many people in IT get pissed with IT jargons and terminologies. More so if it is a customer, especially when he or she is not well versed with the fundamental concept behind the technology architecture.

Even after 20 years, with most of it in storage, I have a hard time switching from one vendor’s jargon to another (sometimes). But it has gotten harder for me lately, since I teach ONTAP courses for NetApp, EMC Cloud Infrastructure and doing my work with the ZFS stuff. Soon, I will take on EMC VNX, Information Storage Management (ISM), Big Data courses as well, and I also plan to do some Nexenta training too.

Who would know that an ONTAP NAS volume would be known as file system in EMC VNX for File (aka Celerra), and a data set in ZFS? Or a ONTAP aggregate is almost like a ZFS pool but with some differences or a clone might be called a replica in HDS and so on …

In fact, all the definitions above could be wrong because I am getting confused. 😉 You would be too if you have to switch from one vendor’s jargon to another. And the poor EMC pre-sales who has not been with any other vendor except for EMC all his career would have a hard time rewiring his brain if he had joined another vendor like NetApp.  Or IBM, or Dell, or Oracle or anyone for that matter.  No wonder the customers are pissed. 

Fear not, because there is help.

Remember the days when we first encountered our first networking lesson. What’s the first thing you and I have to memorize (often by heart)? Look the diagram below and tell me what it is:

Yes, it is the famous OSI 7-Layers. There aren’t many commercial implementations of the OSI 7-Layers (except for maybe the X.25 protocol suite) but it did help us understand networking. It helped us understand what are frames, packets, datagrams, etc without the fancy schmancy vendors’ jargons.

Well, guess what? There is one in storage networking as well, and it is called the SNIA Shared Storage Model (SSM). And it is just as important as the OSI 7-Layers, because it helps us understand the storage architecture landscape and how every piece fits together in totality. It is defined in a common vocabulary and industry accepted standard definitions and terminology, minus all the artificiality of the vendors’ jargons. It is THE STANDARD MODEL for storage architectures. The second and the latest version of the SSM looks like this:

By studying the SSM, anyone (I hope), would be able to understand where each component fits, how they communicate and interact with each other, and the relationships and dependencies that are involved.

When layered with applications and the storage networking technologies, one would be able  figure out the SAN and the NAS, differentiate the components and the protocols and understand the pros and cons, AND the whys of disparate storage architectures. Here are 2 examples of a layered view of both SAN and NAS:

In fact, the division and categorization of DAS, NAS and SAN are very well laid out in the SNIA Layered View below:

The SNIA SSM does not leave out Tape technology as well and have included Tape in a variation of the SSM model below:

There is an old, but very practical example of how the SNIA Shared Storage Model is applied in a real life environment. This article was part of the book called “Designing Storage Area Networks: A Practical Reference for Implementing Fibre Channel and IP SANs, 2nd Edition” written by Tom Clark. Sadly Tom Clark passed away on February 13th 2010 and his blog remained as his online memorial space. Tom has been one of the pioneering stalwarts of SNIA.

I had the honour of meeting Tom in the year 2000, at the Quantum Asia Pacific event in Langkawi. I told him how his book (the first edition) gave me the foundation and solid grounding in storage networking. His book helped me passed my SNIA Fibre Channel Professional certification in 2001.

Sentimental feelings … but back to SNIA SSM.

Coupled with the SNIA Dictionary (recently updated in 2012), the SNIA Shared Storage Model is THE COMPASS for everyone involved in storage, information infrastructure and information management, just like the OSI 7-Layers.