Storage on the edge

Every company uses networked-shared storage, whether it’s implemented as a ring of trusty old file servers or as a speedy, expensive SAN (storage area network). As workloads increase – both the frequency of transactions and the quantity of data to move and store – IT managers are learning that their older storage systems have trouble keeping up. Perhaps the systems don’t meet performance requirements, creating a bottleneck for applications. They may be too difficult to manage, imposing excessive downtime for maintenance and upgrades. Or maybe the problem is finding the right way to protect the stored data.

Storage virtualization

One of the limitations of current storage solutions is that software – operating systems and applications – uses some very old rules to figure out where to store its data. It must still identify storage locations with great specificity, usually involving a combination of network ID and hierarchical path. A company can have a vast quantity of storage on its network, but it’s often split into discrete pools, each of which is managed and accessed separately.

Storage virtualization merges these storage pools in ways that best meet application requirements. It also makes it easier to reallocate storage as needed, even across multiple file servers or SANs. With storage virtualization, you size your storage for the needs of the entire network, not the needs of each class of application.

The benefits are clear, yet storage virtualization is new to most IT leaders. Only seven per cent of the 500 readers surveyed in the 2002 InfoWorld Networked Storage Survey are using virtualization software, and just eight per cent are likely to buy it this year. Only a handful of products exist now, and vendors haven’t done a very good job of describing the technology’s benefits to prospective customers


Performance is a critical consideration in storage design, but it isn’t the only criterion.

iSCSI solves SCSI’s accessibility and distance problems by leveraging existing TCP/IP infrastructures. An iSCSI host adapter turns a server’s SCSI commands and data into network packets and transmits them across the company’s IP network. The advantage of iSCSI is that the operating system doesn’t know a network is involved; iSCSI looks like a local storage device.

Also, iSCSI is emerging as an alternative to Fibre Channel for SANs, allowing companies to deploy SANs using their existing Ethernet cabling. The IETF (Internet Engineering Task Force) has not yet ratified the iSCSI standard, but several vendors are shipping equipment designed against the working draft.

Of these three technologies, iSCSI has gained the most attention. Twenty-six per cent of survey respondents report already using it, and another 25 per cent plan to add the protocol to their enterprise in the next 12 months. When it comes to specific storage devices, 18 per cent of readers have implemented iSCSI tape libraries, and another 11 per cent will likely buy them this year. iSCSI’s transparency plus the quick adoption of Gigabit Ethernet will drive its prominence in the enterprise.


NAS (network-attached storage) appliances bring the convenience of plug-and-play to networked storage. But each NAS unit is an island, so managing several units, particularly performing bandwidth-intensive backups, is a challenge.

NDMP is a cross-vendor standard for enterprise data backups. The standards group, led by Network Appliance Inc. and Legato Systems Inc., intends to get all NAS units and tape devices speaking the same language. In this model, the backup software orchestrates a network connection between an NDMP-equipped NAS appliance and an NDMP tape library or backup server. The appliance uses NDMP to stream its data to the backup device, making efficient use of network resources. NDMP is a voluntary standard, so total product coverage is unlikely, but a critical mass of hardware and software does seem likely at this point.

Some tape libraries with NDMP are already available, and eight per cent of IT leaders surveyed have added them to their mix of storage devices; another five per cent plan to buy them in the next 12 months. NDMP is quite new and its advantages aren’t yet widely recognized.

The progress of storage technology is linked to advances in networks and I/O buses. Rising technologies such as 10 Gigabit Ethernet, PCI-X, and InfiniBand will bring about new approaches to networked storage just as Fibre Channel, Gigabit Ethernet, and 64-bit PCI did. Capacity, performance, and connectivity demands will always rise, but technology can keep up.


Emerging storage technologies

Executive Summary: New storage technologies effectively address limitations in current approaches. Storage virtualization, iSCSI, and NDMP will make networked storage more flexible, more accessible, and safer.

Test Center Perspective: Traditional metrics of storage effectiveness – capacity and performance – are easy to meet with existing technology. But long-term planning should emphasize manageability, interoperability and accessibility as key criteria. Storage virtualization, iSCSI, and NDMP will help you hit those targets.