Storage area network

Frosting the FCoE Cake…

by Dave Graham on November 2, 2009


Czech kind of sponge cake.
Image via Wikipedia

I was advised the other day that a certain manufacturer was adopting a rather interesting model for Fibre Channel over Ethernet CNA licensing.  Rather than simply purchasing a FCoE CNA with all the features (10GbE, iSCSI, and FCoE) turned on, they were going to adopt some sort of staggered licensing model that put each of those features as an option that you could license (and pay for) at a later date.

When I read this, the analogy that sprung to mind was one of, well, cake.  (I’m not a foodie, I just tend to think abstractly of food.) How many people go to a bakery and buy a plain cake that isn’t frosted and that has a payment plan against it?   You’re going to buy a cake that fits with the mindset of what a cake should be; that is, something that is complete and “ready to eat.”  Additionally, you’re probably not going to be interested in a plain cake where the end cost is greater than a pre-frosted cake!  Why would you buy something that required an order of magnitude more effort to get to a final, workable order?  You’d consider someone who bought into this idea as somewhat of a lunatic.

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Why Policy is the future of storage

by Dave Graham on September 20, 2009


As many of you may know, I work for EMC‘s Cloud Infrastructure Group as part of the Atmos solution team. In this role, I’ve been blessed with getting a closer look at where the future of cloud storage is going as well as some of the drivers that will get it there. In this post, I’d like to talk a bit about policy and how this will shape the future of storage. I’m going to keep this as abstracted from product as possible, but where appropriate, I’ll try to show you how products are implementing this technology TODAY.

What is Policy?

By definition, policy is “[an] action or procedure conforming to or considered with reference to prudence or expediency” (dictionary.com for that definition).  When viewed in the context of storage systems and management, policy, then, is the actions (scripted or otherwise) that influence data to provide for retrieval, performance, or manipulation by systems.  In other words, policy is an engine that manages data from start to finish.  Why this is important requires us to look at what the typical management stack looks like today.

Data is created by users accessing programs that are tied to physical and virtual resources.  This generated data is then processed and stored by the programs and their underlying storage I/O layers (LVMs, hypervisor I/O stacks, etc.) onto some sort of storage device (SAN, NAS, DAS, etc.) where it sits until next access.  In essence, once data is created it is considered to be “at rest” until it is next accessed (if ever).  Within this data generation and storage continuum, the process is fundementally simple as generated data is put directly to storage.  However, if the data continues to sit in the same place endlessly, it’s typically inefficient to retrieve and access.  Managing this data was typically a manual process where data, LUNs, and their topologies had to be moved around using array or host-based tools to provide better “fit” for data at rest or data accesses for performance.  This is where policy steps in.

Policy uses hooks into data (also known as metadata) in order to enact controls.  Please see this post for more detailed explanation of metadata.

Why use Policies?

If the previous example shows anything, it’s that the management of data is fundementally…well, boring and manual.  Policy provides a method of controlling the stack of data ingest AND data management while allowing business to continue to generate, retrieve, and manipulate data.  For example, a simple policy that could be enacted against data could be as follows:

if data < 14 days old, store on EFD drives, LUN 11; if > 14 days old, store on SATA drives, LUN 33

Obviously, that’s a high-level abstraction of what the actual process for data control would look like but drives the point home.  What used to be a manual LUN migration policy to “performance” or “store” data now is set based on a logical control structure that can be automagically enacted on the storage system itself.  A working example of this type of policy can be seen in the tiering provided by Compellent and EMC’s FAST systems for storage management.  Pretty cool, huh?

An alternative method of control that isn’t necessary tied to the storage array is the recent introduction of VMware‘s Storage DRS (Dynamic Resource Scheduling) which is enacted against the storage I/O stack of VMware’s vSphere hypervisor.

The Future of Policy

Obviously, my examples are very simplistic in nature but hopefully, they make the policy technology somewhat more accessible.  As far as policy futures are concerned, this is where storage technologies (and even host process management) will be going.  In the future, simple policy creation and enforcement will be a necessary part of storage pool creation and integration as well as the ongoing maintenance and support of storage arrays.

As always, feedback is welcome!

edit: 9/21/09: removed a mis-aligned reference to Atmos storage policy.

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Moving from Block to Cloud: Emulex E3S

by Dave Graham on June 18, 2009


It’s not often that I get excited about technology within the storage space. There are notables, of course, mostly that take my love for high bandwidth interconnects (e.g. Infiniband, Rapid I/O) and mash them up with high-speed storage (EFDs, Fusion-IO). That being said, when it comes to the cloud, I’m absolutely estatic when off-the-shelf components can be utilized to get your data from the realm of block-based storage into the cloud-esque realm of object-based storage. Today, we’ll do a quick high level overview of one such technology gives you the freedom of moving from block to cloud (and back).

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Video Overview of the Qlogic 5802V

January 31, 2009

As much as I like to talk about Qlogic, there are times when you’ve just got to let someone else tell their story.  In this case, Qlogic’s Marty Holmes gives a very thorough video analysis of the SanBox 5802V Fibre Switch.

This is my current switch of choice if you need small departmental Fibre Channel switches that [...]

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Storage Fabric Lifecycles: An Overview

December 12, 2008

Continuing the thread of explaining the roles of storage fabrics that we’ve come to know and love (FCoE, Infiniband, 10GbE iSCSI, etc.), @rjhintz asked the following question:
What’s the expected technical life of a storage fabric install today before it’s upgraded to a new generation or forklifted out?
There are a few significant events that precipitate storage [...]

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