Client computer storage consolidation

Computer Technology Review, Sept, 2004 by David Griego, Donald Harbin

Managing the storage inside desktops, workstations and servers in an office can be a daunting task as each computer has its own disk drive containing data that must be backed up, restored and archived. Most storage management solutions today consist of management applications running on the client with user intervention enabled. By consolidating the client storage to one central location, organizations can ensure that it is managed by IT professionals, providing high-quality maintenance and the greatest possible uptime.

The Need for Consolidation

Today personal computers fill the office with, typically, one computer per user. Each user creates information and saves it on his local drive. If the user's disk drive fails, the data must be restored from a backup. However, backup programs can have serious shortcomings. In some cases, user intervention is required for tagging important data to be backed up, and the user may not have tagged some or all of the critical work. Also, if the user's data is on a disk drive that is attached to the computer, the only way to get the data will be to fix the computer or to remove the hard drive. These scenarios can result in a significant loss of productivity for the user.

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Finally, because each computer has its own disk drive, the applications and operating system must be installed on each client. Users are responsible for getting updates and patches for the OS and applications installed, leading to inconsistent deployment. Rolling out new and updated applications can also be inconsistent. As a result, there may be many different versions of software among the clients in an organization, making data management more difficult.

Consolidating the client's storage to one location provides an opportunity to alleviate these data management challenges. Backups of the user's data can be performed offline and after hours, even with the client computer turned off. Data is backed up using a consistent policy to ensure that the latest version is restored. Consolidated storage can be protected by the use of a redundant array of independent disks (RAID), with the complexity of RAID hidden from the user, and the system maintained by IT experts.

With RAID in place, the loss of a disk drive does not mean loss of data and subsequent downtime. It simply means replacing the disk and rebuilding the array. If the configuration includes a hot spare disk drive, this activity can take place without the user even noticing. In addition, virus checking of data can be handled offline. The latest virus definitions can be applied before running the scan to ensure that all data is as safe as possible. Another benefit of consolidating client storage is the ability to implement a just-in-time storage capacity policy. Storage usage can be monitored for each client, and capacity can be provisioned as needed for each user instead of devoting large amounts of unused storage space to every client.

Still another advantage of consolidated storage is that the centrally located data can be accessed from other computers. This is beneficial when a user needs to be moved, when a user is unavailable to share files, or when the user's computer is down and needs to be replaced or upgraded. Consolidated storage also means that data can be moved within the central storage location for upgrades of equipment or changes in storage policy (for example, migration from RAID-5 to RAID-6).

Lastly, applications and operating system images can be housed in a single location. Less storage is required because these images are not duplicated for every client. Patches and updates can be installed in one place to ensure that all clients are kept up to date.

Implementing a System for Consolidation

There are three basic elements involved in implementing a system for consolidation, as shown in the Figure. The first element is the client side--the computer to which the end user has access. This must be set up with minimal impact to the user so that productivity is maintained. The second element is the network, which connects the client to the storage. The network should be relatively easy for IT to set up and maintain. Finally, there is the storage backend, which houses all of the user's data. This backend consists of both the disk drives and the management applications.

Client Computer: The client computer will be virtually the same as before implementation, with the exception of not having an internal disk drive. This drive is replaced with an adapter that allows a networked connection to the storage backend. There exist several technologies to accomplish this, including Fibre Channel and iSCSI over Ethernet. Fibre Channel is most commonly used in data centers, and requires specialized equipment and cabling to implement. Today, iSCSI over Ethernet is rapidly gaining momentum because it maximizes reuse of existing infrastructure and leverages Ethernet networking knowledge that the vast majority of IT departments already possess. For these reasons. iSCSI will be used as the implementation example in this article.