Grow with the flow

Grow with the flow

Fibre channel switches are the supporting structure of a SAN. Each switch carries its share of the data traffic and works together with other switches to maintain a stable and responsive environment. Removing one of the switches, even for a short time, in a reticular system such as a fabric can initiate a domino effect that causes your SAN to stutter and eventually fail to serve data to business applications.

Such unacceptable failure creates interesting and costly design challenges for storage administrators to build SANs with enough built-in redundancy to withstand occasional "brick" removal, triggered by routine maintenance or updates.

If the above scenario rings true, consider offerings from McData. The company recently announced new versions of director and fabric switches that offer unsurpassed port density and simplified management, which combined with competitive pricing could result in substantial savings.

Two new products from McData are at the heart of the company's storage offering: the Intrepid 6140, a director-class fibre channel switch that packs as many as 140 FC ports in only 9U (16 inches) of rack space; and the Sphereon 4500, a field-extensible fabric switch that can stretch from eight to 24 FC ports without service interruptions.

The Intrepid 6140 will appeal to customers with large SANs because of its unrivalled port capacity and density. However, the Sphereon 4500's unique capability of extending its port capacity in eight-port increments offers an easy update path for companies with expected, although not yet defined, capacity growth.

The Sphereon 4500 also takes advantage of a new, single-ASIC architecture, essentially a single chip that delivers concurrent 2Gbps bandwidth to each port; hence the additional port capacity will not be offset by diminished performance.

For our review, McData sent us a Sphereon 4500 fully populated with GBIC (gigabit interface converter) connectors but in an 8-port configuration. Part of our test script was to try out the FlexPort feature, an online update that increases the number of ports in increments of eight while the switch is under load.

The Sphereon 4500 is a rack-mountable, 1U-tall, square box measuring roughly 17 inches on each side. It displays the 24 FC ports and control LEDs on a double row in the front. The back hosts two hot-swappable power supply units and a serial port that we connected via null modem cable to one of our servers to access the command-line management software and to set an IP address consistent with our LAN.

A built-in HTTP server and an Ethernet port provide connectivity for the included, browser-based SANpilot management software, which we used to configure and monitor the unit. SANpilot's GUI is very intuitive and can easily handle tasks such as partitioning the switch in zones that group specific hosts and storage devices; setting each port connectivity mode, such as point-to-point or arbitrated loop; or monitoring port traffic. You can perform the same tasks using the command-line interface via serial or Telnet connections.

Back to our servers, we set each HBA (host bus adapter) to connect the proper WWN (world wide name), mapped storage devices to volumes in our servers, then began filling those volumes with data. The blinking port LEDs and SANpilot's port statistics confirmed that our switch was under load.

Now it was time to try the FlexPort capability, which allowed us to increase the ports while our switch was still swapping data between servers and storage devices. The procedure is incredibly simple. We obtained from McData a new feature key. (In a real installation you would, of course, pay for expanding your switch.) We typed the key in SANpilot's Feature Installation window and clicked the Activate button.

Seconds later SANpilot displayed the new, 16-port configuration. A quick check of the traffic lights and of our servers confirmed that our simple data transfer had not been affected by the update. We had doubled the capacity of our switch in seconds and the new port range was ready to use. With similar steps we updated our switch to 24 ports and loaded a new firmware. In each case, traffic was uninterrupted.

Our first experience with the Sphereon 4500 was exciting. The switch removes some of the stings of storage management at its roots with a more business-friendly behaviour that puts service continuity (rather than technical requirements) first, as it should. Moreover, McData offers the 4500 at a very competitive price. If you are planning to increase or build from scratch your SAN fabric, the McData Sphereon 4500 should be your favourite "brick".

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