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http://www.oracle.com/technology/oramag/oracle/06-sep/o56field.html
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COMMENT: In The Field Storage Made Simpler 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.
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 IOUG (Independent Oracle Users Group) and senior
consultant for Datalink. He founded Expand Beyond Corporation, a leader in
mobile IT software. He has been involved in Oracle technology since 1992. |
