Storage Virtualization Grows Up: Slowly

By Bob Scheier
published: Monday, October 06 2008

The fact that these massive server pools require ever-larger amounts of storage was lost on some folks at first, but not on storage giant EMC Corp., which hopped on the virtualization bandwagon big-time with its purchase of VMware Inc. back in 2003.  Skepticism about that deal faded as VMware became the juggernaut that still dominates the server virtualization market. It also didn't hurt that these big pools of servers spurred demand for the massive storage area networks EMC sells.

If pooling computing resources is good, the same should be good for storage, allowing companies to quickly and easily divvy up their storage pools among new applications and user groups as needed. But hiding thousands of servers and thousands of storage volumes and LUNs (logical units) under the virtualization blanket can cause some knotty problems. How do you make sure the right server can find the right storage volume when neither of them has a fixed physical address on the network? How do you ensure each customer's credit card info and each of your product plans is protected by the right level of security when their bits and bytes are scattered over multiple storage arrays? How do you set aside enough extra space to store the "state" of a virtual machine so it can recover from a crash without using more space than you've gained through virtualization?

Today, many customers are still treating their physical and virtual environments as two separate worlds when it comes to routine functions like data protection. Backup and security vendor Symantec Corp. polled users at the recent VMworld conference and found that four out of ten are still using two or more products to back up their physical and virtual servers , and more than half still do separate backups for single files and for the full "images" of  virtual servers. This drives up costs and complexity, and balloons the backup "windows" during which applications are unavailable to users.

Fortunately, both established and start-up vendors are working to ease the pain. VMware already offers live (no downtime) migration of both server images and storage. (Microsoft promises to deliver such "live migration" of servers in a future version of its own Hyper-V migration platform.) At VMworld, Symantec introduced version 12.5 of its Backup Exec software, providing backup and recovery for both data and system images, in both physical and virtual environments - and supporting both VMware and Microsoft virtualization environments. Among other updates to its backup software, Hewlett-Packard Co. recently extended the Zero Downtime Backup and Instant Recovery features of its Data Protector software to VMware virtual machines, giving customers "zero impact backup of mission critical application data residing on virtual machines. (This feature currently works only in VMware environments.)

Other vendors offer everything from global file systems and virtualization appliances to ease the pain of managing storage in a virtual environment. Whatever the silver bullet, customers need to keep asking questions such as:

•   Does the product completely eliminate downtime for backup and recovery?

•   Does it provide backup and recovery of both images and individual files?

•   Does it support disks and controllers from any vendor?

•   Does it support all the storage protocols and topologies in my environment?

•   Does it support all the server virtualization platforms in my environment (i.e., VMware, Microsoft, and Citrix XenServer?)

•   Does it provide encryption and/or preserve vital security settings?

Until vendors can answer all these questions - and more - storage virtualization will still be playing catch-up with server virtualization.

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