Virtualized 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 powerful 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 virtualization, vendors have discovered that indirect addressing of a LUN (logical unit number), a key prerequisite for virtualized storage, allows for managing of foreign arrays as seamlessly as their own.
I had an early experience with Invista at one of the EMC labs, and it gave me a pretty good idea of what the product has to offer. 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 US$140,000), EMC’s virtual storage solution plays a tantalizing tune.
Invista’s applications run on intelligent switches located between storage arrays and hosts. On the array side, Invista simulates the behavior of a storage-hungry server; on the host side, it plays the role of a large storage array.
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 virtualization activities.
My Invista instance included two Control Path Clusters (CPCs) — essentially two resilient servers running the Element Manager virtualization software — with local disk space to permanently store virtualization metadata and the EMC software for the two intelligent switches. Intelligent switches are an essential component of Invista. They do the actual directing of virtualized 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 intelligent switches 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 virtualization tasks.
The GUI offers the same functionality as the CLI wrapped in easy-to-use wizards. 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 virtualization features is the ability to move a logical volume from one storage device to another without interrupting applications that are using that volume.
Invista storage virtualization brings a much-needed breath of administrative fresh air to existing SANs. It’s not quite a free lunch, but it could be your most effective investment toward managing storage according to business needs rather than technical constraints.