Enterprise iSCSI SANs

These powerful devices can meet the ever-increasing need for storage

Years ago, I had a Gateway 2000 computer with a 250MB hard disk. Compared with the majority of computers sold at the time, 250MB was huge. Today, after digging through a few junk drawers and boxes, I was unable to find any storage medium that held only 250MB. The smallest storage medium I could find was a long-forgotten 512MB USB flash drive that I received from a vendor about two years ago and squirreled away in a drawer.

Our appetite for storage is ever-increasing, especially as our workloads have changed. In a typical enterprise, the storage needs are as vast as the night sky. If you add up the storage requirements for applications, virtual machine (VM) hosting, backups, and copies of files for regulatory compliance, you can quickly see how my humble 250MB drive is the digital equivalent of a matchbook.

Storage is so important that it's now uncommon to see even small organizations relying exclusively on servers with only locally attached storage. A while back, the only way to break out the storage subsystem was to purchase an expensive SAN. These SANs were almost always connected back to their host servers through a networking technology called Fibre Channel. The primary downside to Fibre Channel was the need to purchase and install equipment that was completely incompatible with the Ethernet installations that most organizations already had in place. Fibre Channel required its own switches and optical cabling. Plus, host bus adapters (HBAs) had to be installed in any server that needed access to the SAN. Many vendors took advantage of this and sold SAN-in-a-box kits that included all the required hardware and cabling, making them an ideal solution for small to midsized businesses (SMBs). Dragone-WIN2588-Fig1-sm

SANs have made great improvements over the past decade. A major improvement was the emergence of SANs utilizing iSCSI as their primary network interconnects instead of Fibre Channel. However, at that time, it was impossible to get the same performance from iSCSI SANs compared with Fibre Channel SANs. In any throughput contest, the Fibre Channel SAN was the hands-down winner. Dragone-WIN2588-Fig2-sm

Over the years, iSCSI SAN vendors have greatly improved their performance numbers. Networking and storage vendors introduced dedicated iSCSI NICs that offloaded the network processing from the host server CPU to a dedicated processor on the NIC. Networking vendors also enhanced their Ethernet switch software, allowing various models to be tuned by means of Quality of Service (QoS) settings to ensure that networking traffic dedicated to storage received the highest throughput and lowest latency. Dragone-WIN2588-Fig3-sm

Improvements in related areas have also helped improve iSCSI SAN performance. Server vendors introduced models with multiple onboard NICs, some of which featured iSCSI offloading, negating the need for a dedicated iSCSI NIC HBA. OS vendors, including Microsoft, built iSCSI initiators into their offerings. And most organizations have segregated their networks into multiple Virtual LAN (VLANs) to separate traffic types, especially voice traffic. Many organizations also have multiple physical Ethernets to isolate their management traffic from production traffic and storage traffic. Finally, with 1GB Ethernet being the current standard and 10GB Ethernet quickly making inroads, it's easy to see why iSCSI SANs are such a popular choice today. Dragone-WIN2588-Fig4-sm

If your storage needs have grown beyond what you can comfortably handle with locally attached storage, I encourage you to take a look at some iSCSI SANs, such as the Drobo B1200i, the FalconStor Network Storage Server, Dell's EqualLogic Storage, or one of HP's iSCSI SAN solutions. It's likely that you already have a lot of the plumbing already installed or readily available and can take advantage of this storage technology in short order. Check out Table 1 for a glimpse at the current iSCSI SAN market, along with links to the information you need to make an informed decision.

Table 1: Enterprise iSCSI SAN Solutions




Compellent zNAS


EqualLogic Storage




xStack Storage


Drobo B1200i

Enhance Technology


FalconStor Software

FalconStor Network Storage Server


HP LeftHand P4000 Storage


iSCSI SAN solutions


Data storage systems

Qsan Technology

RAID Systems

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