Hewlett-Packard

There’s a lot of confusion about storage virtualization, including misperceptions and even myths. Ready to sort fact from myth? Read on.

Myth: There is only one “right” way to do storage virtualization.

Fact: There is no single right way to do storage virtualization, because it is not a single technology.

Rather, storage virtualization is a concept implemented through different methods, both alone and in combination.

At the highest level, virtualization is the logical representation of physical resources as pools rather than individual devices. Servers, applications and other agents can draw from these pools what they need without regard for the origin of the resource at hand.

By obscuring the complexity of underlying hardware, virtualization simplifies and standardizes the use of IT resources, such as computing cycles, bandwidth or, as discussed here, data storage space.

Storage virtualization can be implemented at three different levels:

1. Server
2. Network
3. Storage device

Each level offers its own pros and cons, and, even within each level of virtualization, there are multiple technologies at work.

1. Server
In server-based storage virtualization, software running on the server causes the operating system to behave as if it were in communication with a physical storage device, rather than a virtual disk. Serverbased storage virtualization offers an effective solution for small and entry-level systems because it is simple to use. However, unlike other forms of storage virtualization, the server-based variety uses server resources which may also be needed to run applications. In addition, server-based storage virtualization may not be available in all operating systems.

2. Network
Network-based virtualization—usually in a storage area network—can unite disparate array subsystems into a single storage pool, extending the size and reach of the storage pool considerably. In a SAN, the virtualization happens either in a SAN switch or a virtualization appliance.

3. Storage device
At the storage device level, virtualization is implemented at the disk array controller. The controller creates logical storage volumes from the pooled capacity of many different physical disks. Servers interact with these virtual disks as though they were physical disks. Storage device-based virtualization offers businesses a good balance between simple implementation, capacity, speed and functionality, but the main benefit is to simplify the management of the storage device.

There’s no one-fits-all solution. In fact, storage virtualization technologies are often deployed in combination, or even layered, to deliver the greatest possible benefits.

Still, storage device-based virtualization is often the easiest to implement and promises great speed, capacity and flexibility.

As a result, virtualized storage arrays are popular choices for implementing storage virtualization today.

Download the whitepaper: HP Storage- Works virtualization whitepaper (PDF, 1.55MB) at: http://h71028.www7.hp.com/ ERC/downloads/4AA0-7358ENW.pdf

Myth: Virtualized storage can be complex to manage and requires a lot of storage expertise.

Fact: Virtualized array storage simplifies storage management, improves capacity utilization and minimizes training requirements.

In fact, some experts stress manageability as a major advantage of virtualized storage: “The single most important attribute of any storage virtualization solution is the ability to mask complexity and thereby make manageable that which is increasingly becoming unmanageable,” says John Webster, principal IT advisor at analyst firm Illuminata.

Managing a virtualized pool is easier than managing its components individually.

In a virtualized array system, administrators deal with the attributes of storage rather than the mechanics of storage management. Let’s say you want to add more storage capacity to your e-mail application. With a traditional storage array, that means manipulating arcane disk and array settings manually while being mindful of technological limitations and caveats.

With HP’s virtualized storage system, the Enterprise Virtual Array, the administrator need only know the desired outcome— increase e-mail storage by a certain amount.

The EVA does the rest. Thus, the EVA requires less management and managers require less training.

Just as important, virtualization allows the EVA to spread data across more spindles (disks) than traditional RAID, increasing performance through automatic load balancing.

Redundant arrays of inexpensive disks, or RAID, can speed data input/output by striping data blocks across groups of physical disks simultaneously. The EVA takes RAID virtualization a step further, striping data across all the disks in the array, regardless of disk capacity or RAID protection type. Using an on-the-fly leveling algorithm, the EVA balances performance by spreading data in each virtual disk evenly across all of the spindles, practically eliminating socalled “hot spindles.” (Hot spindles occur when frequently accessed data is stored on just a few intensely used disks.)

Need more capacity or performance? Add more disks. The EVA automatically integrates them into the virtual pool, redistributing data across the drive pool.

Not only does the EVA’s virtualization technology improve management and performance, but it aids in reliability and recovery by creating a flexible storage pool that can not only grow, but also shrink as necessary.

Download the white paper: Be green with the HP StorageWorks Enterprise Virtual Array (PDF, 276KB) at: http://h71028.www7.hp.com/enterprise/ cache/504592-0-0-0-121.html

Read more about the HP EVA family at: http://www.hp.com/go/ev

Myth: Storage virtualization is too complex and expensive for midsize businesses.

Fact: That might have once been true, but not anymore.

With emerging storage array virtualization devices such as the EVA4400, midsize businesses can’t afford not to implement virtualized storage.

In the past, midsize businesses had two choices:

• Pay a premium for enterprise-class storage arrays (and hire an enterprise-sized staff to attend to the storage infrastructure).
• Pay less for a less complicated solution, and miss out on higher levels of capacity and functionality.

The EVA4400 nearly eliminates those tradeoffs. This EVA is designed to simplify and automate midsize storage environments. We like to call it “the storage array you’ve always wanted, but could never afford.” In other words, the EVA4400 gives you the enterprise-class functionality you need with documented simplicity and at an affordable price. Visit http://www.hp.com/go/EVA4400 for more details.

This entry was posted on Wednesday, April 30th, 2008 at 5:26 pm and is filed under Article.