Cisco's first storage switch raises the bar

Cisco has entered the storage market with a bang, introducing a feature-rich, director-class switch that in our tests delivered some of the best performance metrics we've ever recorded. In an exclusive Network World product test, the 112-port Multilayer DataCenter Switch (MDS) 9509 demonstrated wire-speed throughput for small and large frames at 2G bit/sec rates.

The MDS 9509 also sports some noteworthy features, including support for virtual storage-area networks (VSAN), a Cisco innovation that contributes to high availability and scalability.

This combination earned the MDS 9509 our World Class award.

We tested Version 1.0(1) in mid-December when Cisco released gold code. The product will not be widely available until IBM starts reselling it as part of a deal the two giants announced this week.

Management was not only excellent, but also is supported on the MDS 9509 at no extra charge. Cisco says per-port pricing will cost about US$2,000.

The MDS 9509 is a modular, multislot chassis with two slots for the switch fabric and seven switching module slots that can accommodate MDS series blades. It is a 2G bit/sec Fibre Channel system, and that is the rate at which we tested it. But like other Fibre Channel switches, it can autonegotiate down to 1G bit/sec.

While multiple protocols, including Fibre Channel over IP, Internet over Fibre Channel Protocol and iSCSI, are supported on the MDS 9509, FICON and ESCON are not. Without FICON - which is essentially ESCON over Fibre Channel - the MDS 9509 won't be able to network with IBM mainframes. Cisco says FICON support is planned, but did not provide a time frame.

Performance details

  • In a 30-second test using large, 2,148-byte packet frames, bidirectional per-port throughput was 210M byte/sec on all ports, which represents 100% line rate.

  • With 60-byte frames, under a 100% delivered load on all 112 ports, raw throughput was 150M byte/sec per port, which is 98.7% of the bidirectional theoretical line rate - the highest we've ever observed on director-class switches in a multiport test using small frames.

In these two tests, traffic was delivered on one port and came out on another port on the same blade. In our next tests, traffic went into one port and came out on another port on a different blade. This forces the MDS 9509 to switch traffic between ASICs through the switch, which let us check for blocking within the switch's fabric. The MDS 9509 proved to be totally nonblocking, even in our full-mesh tests.

In a full-mesh test using large 2,148-byte frames, we had 100% theoretical maximum throughput, which we have observed on director-class switches from McData and Brocade - but only when running at 1G bit/sec. The tests on the Cisco box were conducted at 2G bit/sec.

The MDS 9509 had a maximum latency of 219 microsec when tested with large frames. We've seen director-class switch latencies ranging from 174 microsec to more than 600 microsec.

For redundancy, this product ships with one MDS 9509 Supervisor-1 CPU card (a second is optional) that supports nondisruptive code load and activation. Nondisruptive code load is the ability to upgrade the firmware or core operating software without downtime.

When we've seen this feature demonstrated on other SAN switches, it was performed by upgrading a back-up CPU, then failing the system over to the upgraded module. In this case, the hot-upgrade was performed on the same, primary CPU. This took only 15 seconds for the hot firmware upgrade with no lost frames. We noted that when one Supervisor card failed, the other optional card kicked in instantaneously.

Other hardware redundancy features were a little thin. For example, there were no redundant fans, although the fan tray is hot-swappable. And while the power supplies can be in a redundant configuration (N+1), other vendors have demonstrated high-availability configurations (N+3).

Virtual SANs

With this product, Cisco introduced the VSAN, which basically takes the concept of Fibre Channel fabric zoning a step further. Fabric zoning allows for the creation of device zones, or groups, within a switch that cannot connect to or communicate with other devices outside that zone. It's a way of isolating one group, or zone, from another for security purposes. However, the segmentation is not complete because it takes place within the same database on the switch that enforces the zones and provides addressing and routing functions for each. A malfunctioning node on one zone, for instance, can corrupt the database and bring down the whole SAN.

VSANs have the ability to segment the database. That means each defined zone is a discrete storage network with its own dedicated database. So if one VSAN experiences trouble, it doesn't affect the other VSANs defined within the switch.

Other applications for VSANs would be to interconnect isolated fabrics in remote data centers over a long-haul link. They also add to the switch's scalability and the creation of multiple SAN "islands," eliminating the need to use a separate switch fabric for separate applications.

Management

The MDS 9509 is managed through a command-line interface, which has the look and feel of a Cisco IOS CLI. Management also occurs through Device Manager and Fabric Manager, two Java-based Web interfaces that can be downloaded directly from the switch.

Device Manager is a top-level interface that shows the switch's physical configuration and status on individual ports. It graphically displays all elements, and lets you configure elements or groups of elements on the switch.

Fabric Manager provides autodiscovery of the SAN topology and presents it graphically. You can monitor network health and traffic, view traffic statistics, and view network element inventories from one location. It also allows for management and configuration of interswitch links.

Network World is a US-based affiliate publication produced by IDG Communications.

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