SAN Switch Solutions


Storage Area Network (SAN) installations are as diverse as the businesses they serve. To enhance the range of solutions it provides, Unylogix Technologies has developed various models based on various products and which offer a unique set of product features essential to the deployment of quality SANs.

The descriptions below correspond to the requirements of specific customers and indicate the broad spectrum of end-user problems that can be solved using Fibre Channel switches.

  • Enterprise SANs -- Scalable, highly-available environments impacting the productivity of multiple areas within a company. (Data security is often a prerequisite for success.)

  • High-performance SANs -- Immediate performance boosts for applications with high bandwidth needs (Video editing, medical and seismic imaging, etc.)

  • Low-cost SANs -- Basic SAN connectivity at the industry's lowest price point.

 
Enterprise SANs



 Fig. 1 -- As the Enterprise SAN changes and grows, end-users will expect the system to maintain its original performance, reliability and management attributes.
Multiple applications

  • UNIX, NT or Mainframe platforms

  • Server or storage consolidation

  • Heterogeneous server clusters

  • Online transaction processing (OLTP)

  • Backup or remote site disaster recovery


  • Customers whose solutions encompass multiple enterprise activities must maintain availability and security within a constantly changing environment. To provide long-term value, these customers require a SAN fabric that can adapt to the normal transitions of an organization while satisfying user expectations of consistent performance and ease-of-use.

    One such solution by QLogic provides one of the most highly available and "future proof" fabrics on the market. Built with enterprise needs in mind, QLogic's SANbox products help SAN architects plan for the inevitable evolution of their designs.

  • Availability

    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

  • Scalability

    QLogic's Director-class products provide modular scalability within a single chassis. In addition, QLogic's unique Multistage cross-connect capability allows networks to expand without adding the "hop" latency and congestion intrinsic to all other multi-switch topologies (See Multi-switch tech brief). Fabric capacity actually grows as switches are added, while overall latency remains constant.

  • Management

    Superior multi-chassis management tools let users "see" at the fabric, switch or port-level, unrestricted by platform or operating system. QLogic's intuitive Web-based interface is supported by an open systems architecture that easily integrates to a customer's GUI of choice.

    Specific management features include "hard zoning," an QLogic-exclusive which establishes ironclad security between technologically differing areas of a SAN (say UNIX and NT segments) or in heterogeneous environments where confidentiality of information is essential.

  • Interoperability

    Proven interoperability with most major adapter, storage and software vendors plus long-term customer experience with IBM, Sun, HP and various NT server installations gives QLogic fabrics the additional advantage of compatibility with heterogeneous environments.

    SANbox FLSTM (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.

  •