Multiple switch-to-switch links enable topologies with no single point of failure. Hot-swappable parts and self-discovering, self-configuring ports allow repairs and expansion while the network is still up and running -- practically eliminating the possibility of user down-time.

QLogic advantage More scalable Easy installation and growth -- self-configuring fabric Platform independence -- Web-based multi-chassis management High interoperability More reliable -- build topologies with no single point of failure

SANbox FLS^TM (Full Loop Support) leverages past infrastructure investments by bringing legacy private loop devices forward into a full fabric environment. Only SANbox FLS facilitates transactions between all combinations of fabric, public and private devices.

 

High-performance SANs

Applications Video editing and movie production Medical imaging CAD/CAM Geoseismic imaging Defense applications

QLogic advantage 100MB/sec (full-duplex) connection at every port ASIC-embedded buffers (faster than shared memory architecture) Latency under 500 nanoseconds 2KB frames with in-order delivery regardless of topology

Faster than a hub

True full-duplex Fibre Channel switching produces aggregate speeds not possible using shared-media hubs. Although QLogic switches support FC-AL ("loop") protocol at every port, bandwidth arbitration among devices on a single port does not affect the performance of the rest of the system. Individual servers or storage devices still receive the dedicated 100MB/sec links necessary to run powerhouse applications like HDTV video editing -- all within the stable, manageable setting only a switch can sustain. (See "Low-cost SAN" section.)

Faster than any other switch

SANbox switches are the best-performing switches in the industry, thanks to QLogic's highly integrated multi-port ASIC. "Memory on the chip" (instead of the more common shared buffer architecture) saves transfer time and contributes to an ultra-low switch latency interval. Roomy 2KB frames and guaranteed in-order frame delivery maximize Fibre Channel's built-in efficiencies.

These benefits, already significant in single-switch fabrics, can become critically important in multi-stage or cascaded environments.

 

Low-cost SANs

Applications/Requirements Low-cost servers/storage Server or storage consolidation Sustainable performance with limited IT personnel resources Cost-effective, incremental scalability Support for legacy environments

Cost has always been a principal force driving the development of SANs. The prospect of financial savings via pooled storage resources, incremental hardware scalability, and centralized management is now leading more organizations than ever before to explore new storage strategies.

Until recently however, state-of-the-art SANs were not affordable for many small and mid-sized enterprises. Switches were prohibitively expensive and hubs, deployed in a few early SANs, did not meet the performance and stability needs of business-critical applications (see below).

QLogic advantage Switch at hub prices Loop support for low-cost storage Low-cost scalability add devices incrementally cascade switches Low lifetime costs Easy installation and management

QLogic has led the move to eliminate the cost barriers to high-performance SANs. With entry-level switch prices now approaching those of managed hubs, companies have little reason not to begin the migration to a robust, full-featured storage infrastructure.

The Hidden Cost of Hubs

Hubs, once considered a low-cost alternative to switches, have limitations which significantly affect their true cost of ownership. Hubs not only share bandwidth -- they also share the instability of each of the devices they link.

In FC-AL protocol, whenever a device enters a loop, it sends out a loop initialization primitive (LIP) to request an address. All other activity on the loop then comes to a complete stop as each device reestablishes its connection within the new configuration.

Since a hub-based SAN is actually one large loop, it must be entirely rebuilt every time a device -- even a single JBOD drive -- is added or removed. Processing errors, disk failures or simply rebooting a device can all incur LIPs. Worse, a phenomenon called a "LIP storm" can cause multiple devices to send non-stop streams of initialization commands, requiring a great deal of cost-intensive hands-on attention by IT personnel until the problematic disk or adapter is located and the loop restabilized.

Switches are stable

Switch fabrics, on the other hand, are easy to maintain and relatively inexpensive to own. While hubs are only as strong as their weakest link, switches allow IT planners to install as much fault-tolerance as they need by isolating potentially unstable or periodically reconfigured devices on their own loop segments. Swapping drives on a switch-attached JBOD, for example, only causes the JBOD itself to reinitialize -- the rest of the SAN maintains full connectivity and performance.

QLogic's reliable products create additional lifetime cost-savings due to their inexpensive scalability options, plug-and-play ports and easy-to-use fabric management tools.

The overview of the SAN solution above specifically used the Qlogic products as examples. Attributes of the QLogic fabric solutions described above as well as our other fibre fabric switch solutions can be applied in various combinations to meet the needs of any real-life storage networking project. Flexibility and the industry's most powerful feature-set makes Unylogix Technologies the first step toward the profitable deployment of effective SANs.