COMMENT: In The Field

Storage Made Simpler
By Ari Kaplan

Storage virtualization can simplify database applications.

Some vendors—and even customers—might think that there's no story in storage. You have hard drives. You store data on them. End of story.

Unless you have multiple operating systems and servers trying to access the same data. Or your company is struggling to consolidate hardware or software from a merger or an acquisition. Or you need storage-based replication or disaster recovery options. Or you want your storage solutions to be easier to manage. Then storage becomes a big story.

Storage virtualization—which uses collections of disk drives, possibly in a storage-area network (SAN) or a network-attached storage (NAS) arrangement as a unified pool of storage—can be a solution to all these problems. However, drives in that storage pool can use all kinds of protocols: Fibre Channel, iSCSI, NFS, and others. And they can come from multiple vendors and represent different classes of storage. How can you get all these storage systems to work together as one?

The answer is a virtualization solution such as a vfiler —a piece of hardware attached to a network. The vfiler acts as a metalayer between the physical drives and software. This abstracts the storage layer from its physical basis and makes it available to the software.

The vfiler receives all requests for storage, from applications and databases, for example, and translates those requests into the physical locations of the data. The vfiler can address data on a file level or block-storage level, and the data can be local or remote. Thanks to the vfiler, applications can find the data they need, wherever it is. A vfiler solution also enables companies to add and remove storage behind the scenes without downtime or major storage reconfiguration.

One of my clients, a financial services company, used a storage virtualization strategy and found how much it simplified maintenance. These people constantly move their storage devices and other equipment around. In the past, they had to call in expensive specialists to move, rewire, and configure physical racks of storage as needed. Now the company's virtualization solution automatically manages the storage environment, and because adding to or removing from the pool is easy and entails no downtime, the company saves time, money, and energy. What used to take days now takes minutes.

Using storage virtualization to intercept and carry out all the storage requests entails almost no performance degradation, because applications must be steered to needed data anyway. With storage virtualization, they are just steered to a larger multiprotocol unified pool of data.

Storage virtualization also allows companies to use their storage space more efficiently. In the usual setup, each database for each application allocates its own island of storage, reserved exclusively for its own use to support that application. Thus lots of storage space is wasted, because the applications don't use the maximum allocated space. However, if the applications can share a single pool of storage, the amount of preallocated space can be reduced. Less physical space is needed, which cuts costs. In my experience, companies recover their investment in storage virtualization in less than a year.

Beyond using space more efficiently, another benefit of storage virtualization is abstraction, such as accessing data across operating systems and storage devices from different manufacturers. I once worked with a high-end cosmetics retailer that needed assistance with its integration efforts. The company ran applications on both UNIX and Windows machines, but data management issues frustrated managers: UNIX applications couldn't handle Microsoft Word documents, for instance. But by using storage abstraction techniques, the applications could see and manipulate files as necessary, all behind the scenes and invisible to the users.

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Oracle's Automatic Storage Manage-ment (ASM) complements storage virtualization. ASM keeps track of RAID (redundant array of inexpensive disks) striping and mirroring, so separate storage administration isn't necessary. Because ASM automatically manages much of the storage layer from within the database, allocating storage as needed, applications don't halt when space "runs out." The combination of ASM with storage virtualization makes sense for many shops.

Standards for storage virtualization are evolving. Network Appliances seems to be taking the lead, supporting four popular protocols—CIFS, Fibre Channel, iSCSI, and NFS—as well as NAS, SAN, and Oracle-specific management solutions. The adoption of standards should make storage virtualization techniques more valuable, and the companies that implement some sort of virtualization can expect to simplify their operations and save money. And that's a good story.


Ari Kaplan ( ari_kaplan@ioug.org ) is president of the Independent Oracle Users Group (IOUG) and senior consultant at Datalink. He founded Expand Beyond Corporation, a leader in mobile IT software. He has been involved in Oracle technology since 1992.


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