In the storage networking space today, a finite number of architectures exist. Yet few definitions exist as to the types of storage networking architectures available. This column lays the groundwork by defining two concepts that underpin storage networking architectures.
The first concept involves the nature of the communication occurring on a storage network. Storage networks enable computers to communicate with storage devices. This contrasts with data networks that enable communication between two or more computers. Storage networks compare favorably to data networks in that they both use network protocols to move the data. But these two network types differ in the nature of the data. Storage networks move the only copy of the data while data networks usually transmit a copy of the data.
This distinction may seem minor but it makes a great deal of difference. In a data network architecture, when Computer A sends information to Computer B, if Computer B never receives the data, no worries. Computer A already owns a copy of the data and Computer B may request another copy. Not true in storage networks. If Computer A sends data to its storage device and it never receives the data, the data may be lost since, the storage device lacks the ability to know it never even received the data. The responsibility for the successful sending and storage of the data rests strictly upon Computer A. This concept, though simple, must be incorporated into the design of a storage network.
The other concept that may get overlooked in a storage network design involves the management of the data itself. Data networks only concern themselves with the management of the data in flight between the computers. Here again, storage networks differ.
Storage networks concern themselves with three items. First, the management of the data on the storage devices; second, which computer owns which piece of data; and third, on which storage device does the data resides. This level of data management exceeds the design of most modern day data networks.
Understanding storage network architectures means understanding these two concepts. First, computers communicate with storage devices, not other computers. Second, storage networks manage the data at a higher level than what exists in today's data networks.
Next month: A look at the first of five architectures based upon these two design assumptions.
About the author
Jerome Wendt is a independent writer and storage analyst specializing in
Open Systems storage and storage area network technologies. He currently
manages storage and explores new storage technologies for a large
organization in this capacity. Jerome may be reached at jerome.wendt@worldnet.att.net.
