Virtualised storage is hardly new, but it has been reinvigorated by interesting solutions from major vendors, such as Hitachi's TagmaStore and IBM's SAN Volume Controller.
You can now count EMC as a member of that crowd, thanks to the recent launch of Invista, its new virtual storage solution. Invista offers a rich set of features that take advantage of the capabilities of intelligent switches from Brocade, Cisco, and (in the future) McData.
Although increased efficiency and more effective administration are the more obvious benefits of storage virtualisation, vendors have discovered that indirect addressing of a logical unit number (LUN) - a key prerequisite for virtualised storage - allows for managing of foreign arrays as seamlessly as their own.
Invista brings an unrivaled level of simplicity to managing EMC storage; administration tools make previously unthinkable feats possible, such as moving a LUN without disrupting running applications or easily migrating data across different arrays.
Understandably, both vendors and customers are intrigued by the new possibilities offered by storage virtualization, because it can extend the life of existing assets. That's music to the ears of many CEOs, and considering that a single storage box can cost more than Invista (which starts around $US140,000), EMC's virtual storage solution plays a tantalizing tune.
The virtual Invista's applications run on intelligent switches located between storage arrays and hosts.
My test bed included LUNs from Symmetrix and Clariion boxes, as well as application servers running Windows Server 2003, one of which doubled as the management station for my virtualisation activities.
My Invista instance included two CPCs (Control Path Clusters) - essentially two resilient servers running the Element Manager virtualization software - with local disk space to permanently store virtualisation metadata and the EMC software.
Intelligent switches are an essential component of Invista. They do the actual directing of virtualised traffic according to the EMC code they run and the metadata and tables defined by Element Manager. The intelligent switches are an open platform, able to run storage applications developed by other vendors. A minimum of two is required in a resilient configuration; my configuration had two Connectrix (Brocade) AP-7420B switches.
Invista's management tool is a Java-based GUI that runs either as a stand-alone application or inside a browser window. Invista also has a friendly and comprehensive CLI with extensive online help, an obvious choice for scripting virtualisation tasks. The Invista GUI offers the same functionality as the CLI wrapped in easy-to-use wizards, but adds an intuitive tree view of physical and virtualised resources that simplifies monitoring and administration. Lining up virtual ducks, I was immediately comfortable with the Invista GUI, and quickly learned how to create logical volumes by allocating storage from storage elements (in essence, LUNs), and how to group homogeneous virtual resources in virtual frames.
One of Invista's more interesting virtualisation features is the ability to move a logical volume from one storage device to another without interrupting applications that are using that volume.
Without virtualisation, moving a volume often means stopping the application, moving the volume, then restarting the application and changing it to look at the data's new place.
To simulate moving a volume while an app is running, I created a virtual volume from a Clariion storage element, assigned the volume to my host, and filled it with files. Among those files was a movie clip that I kept running.
Back at the Invista console, I clicked on the new volume and chose "move"; Invista asked me to choose a target location and a data rate for the move (allowing for either low network load or faster completion). The move went off without a hitch, and the movie clip never experienced a hiccup - a good indication that even the most demanding application should not be affected.
Invista's powerful virtualisation simplifies some administrative tasks, such as moving data to a faster array, without painful disruptions to your business. This alone should justify the nontrivial investment needed to acquire Invista.
But there's more. For example, you can clone a volume and create a constantly updated mirrored image that can be detached and assigned to a different task (development, data mining, backups) at any time.
Invista also has powerful features to create new virtual volumes and dynamically extend one that's running out of space. For the latter to be useful, however, your server OS must be able to play along.
Preserving current data is another concern. Invista can import existing volumes into a virtualised environment without affecting the data.
To mark the difference in performance, I measured the transfer rate with Iometer before and after importing the volume. Adding the nonvirtualised LUN to my Windows host, formatting a volume, and filling it with data was nothing new. After running Iometer and saving the test results, I added the LUN to the zone managed by Invista.
With the new zoning complete, I clicked the rescan button on the Invista GUI. The new LUN appeared immediately in the tree. As expected, the data content of the volume was unaffected.
In the zone
After evaluating Invista, my only want is for better integration with EMC's ControlCenter SRM software and other management tools.
As it is now, you must switch management consoles when moving outside Invista, for example, to define a new LUN on a Clariion or Symmetrix array, or to change zoning.
However, I wouldn't be at all surprised to learn that EMC has already chalked that in for future releases.
EMC Invista emc.com Excellent 8.7
Criteria Management (worth 20%) 8 Performance (worth 20%) 9 Scalability (worth 20%) 9 Ease-of-use (worth 10%) 9 Interoperability (worth 10%) 9 Setup (worth 10%) 8 Value (worth 10%) 9
Platforms: AIX, HP-UX, Linux, Solaris, Windows, VMware
Bottom line: EMC enters the virtualisation arena with a solution that runs on intelligent switches from major vendors and that integrates with most popular arrays. The combination promises to preserve customers' investments in fabric equipment and storage gears without sacrificing manageability, performance, and scalability. With Invista, EMC is dealing a hand that many customers will be happy to play.
For the basic 50TB configuration, pricing starts from $300,000, which is for virtualizing 64 TB, including all Invista hardware and software.