Features - Storage Innovations:

BROCADE PLANS iSwitch TO ENABLE 'VERY LARGE' SANs
By Simon Robinson

Faced with growing scalability, availability and management demands from customers as SANs become larger and consequently more business-critical, Brocade is planning to add a number of new features and products to its portfolio, starting early next year.

First up will be support for 'hot' code-load in Brocade's Silkworm 12000 and 3900 fabric switches, which will be shipped to OEMs in the new year. This will provide customers with a 'belt and braces' solution to maintaining switch availability when upgrading networks with new firmware, since they will be able to use it in addition to existing fabric redundancy. Brocade says it will also allow customers with high resiliency -­ but not quite mission-critical -­ requirements to update their networks with no interruption. Also planned for early next year is support for the ESCON mainframe connectivity standard in the 12000 series.

Additionally, although further out, Brocade is planning to introduce technology to simplify SAN management by carving large SANs into smaller, more manageable and more autonomous chunks. Its Internetworking Switch, or 'iSwitch,' is still in early development, and its exact form has yet to be decided, but Brocade believes it will tackle some fundamental management issues that arise when SANs begin to scale up to and beyond several hundred ports.

Impact assessment:

The message

Brocade is planning a number of new features for its family of fabric switches. Hot-code load capabilities and ESCON support will be available early next year, and further out the company is developing an 'iSwitch' device that will seek to address some of the scalability and management issues that arise when SANs get very large.

Competitive landscape

Increasingly, competitive pressures are having an impact on Brocade. McData has used its own hot code-load capabilities as a competitive advantage over Brocade, and Cisco appears to be leading the charge from a scalability perspective through its own Virtual SAN technology, at least from a marketing perspective. McData is muddying the waters by claiming that it already has these capabilities.

The451 assessment

The availability of hot-code load and ESCON support adds customer check-box items to Brocade's technology stack, and should be welcomed. As far as the iSwitch is concerned, it's still early on, and Brocade argues it has plenty of time to come to market before a material number of companies are going to face serious problems regarding scale. However, Cisco's presence is yet another reminder that Brocade is coming under more competitive pressure than ever before.

Context

Brocade says the evolution process of storage networking is analogous to that of data networking, and that storage networks are now reaching the point where scalability is beginning to crop up as an issue from a management perspective in very large environments, just as it did with data networks. Initial SAN deployments, like early LANs, were purely about connectivity, providing the means to attach servers to storage arrays.

Over time, enterprises ended up with lots of small, discrete LANs; something that is also present today in the form of SAN 'islands' in the storage networking world. Discrete islands allow companies to isolate different applications within their own fabrics, increase security and also reduce the impact of disruptive events, since they are limited to a single fabric. More practically, it is easier to build a smaller SAN using equipment from just a few vendors than it is to mix together server, switching and array products from multiple vendors and manage it all in a larger SAN.

However, as storage networks grow, SAN islands become increasingly inefficient since each additional fabric means more (underutilized) hardware, and software needs to be bought ­- and an additional management overhead arises. It also makes it very difficult to reassign underused ports from a separate fabric to one that is experiencing difficulty keeping up with demand.

Opportunity

Therefore, as in the data networking world, Brocade says there is a requirement to "network the networks," to improve the flexibility and efficiency of storage networks. This consolidation throws up questions of manageability as SANs get larger, and Brocade says some organizations with very large SANs are now looking for ways to ease the management burden through greater simplification.

There is an argument that the additional challenges of scale cannot be satisfied by current SAN management techniques, such as zoning. While zoning is a necessary means of providing security for devices sharing the same fabric, it does little in the way of addressing scalability or availability. This is important, since fiber channel imposes a limit on the number of domains per fabric -­ currently limited to 239 domains (or switches) -­ and the number of ports per domain, effectively limiting the size of the fabric. Zones still reside in a common fabric and as such are limited in size by the scalability of the fabric.

Zoning can reduce some of the extraneous traffic that takes place between devices, such as notifications of registered state changes, by restricting this to a single zone and not across the entire fabric, therefore causing fewer potential disruptions to the fabric as a whole. However, since some array interfaces may reside in several zones simultaneously, zoning does not provide complete protection.

Strategy As a result, Brocade is developing an internetworking switch, or iSwitch, to enable subnetting regimes in very large SANs. The company believes SANs will continue to be deployed as small SAN islands -­ along vendor-specific, geographical or 'political' lines -­ but will increasingly need to share their resources to become more responsive to changing requirements.

As such, Brocade views the iSwitch residing at the "boundary point," although whether this will be a physical or logical device remains to be seen. The early indications are that Brocade is struggling over whether to implement the iSwitch as a management blade in a core switch, or as a separate, independent device that will physically sit between multiple SAN islands. Management and security software is also expected to feature heavily.

The main point is that each SAN island will still be managed separately, but will have the ability to communicate with each other to serve resource-sharing, to reduce traffic flow across the entire network and other objectives. Geographically dispersed SANs would communicate over optical cable using DWDM, or IP using FCIP. Brocade isn't divulging details of when the iSwitch will be available, but we don't expect anything until the second half of 2003 at the earliest.

Competition

Brocade isn't the only storage networking infrastructure vendor to raise the issue of managing scalability in very large SANs. Indeed, Cisco is touting its own proprietary Virtual SAN (VSAN) as a competitive differentiator in its forthcoming MDS 9000 family of fabric switches and directors, which are due to be available very shortly. VSAN will be a feature of the MDS family ­- rather than a separate offering -­ which Cisco says will allow companies to build larger consolidated fabrics by logically separating individual environments on top of the redundant, physical SAN infrastructure. This means fewer fabrics need to be built, as each can provide multi-application access and 'island-like' isolation. Spare ports can also be reassigned on the fly to other VSANs using this 'virtual' infrastructure.

The main drawback to this approach appears to be that traffic cannot cross two or more VSANs, since each VSAN is effectively a separate fabric. Cisco says it partly gets around this by offering trunking so that multiple VSANs can share the same inter-switch links (ISLs), reducing the total number of ISLs required and also offering some rudimentary traffic-shaping capabilities. This means VSANs with high-priority traffic can be given precedent over those with lower-priority traffic.

For its part, McData says competitive efforts to provide scalability and manageability are little more than "catch-up," and that 1,000-port-plus SANs using McData directors and switches are far from uncommon. It says its serial cross-bar architecture (a technology that Cisco is also adopting) already allows for any-to-any connectivity, and that it can "bind" SANs at a node, switch and fabric level to effectively create multiple SANs within a SAN. It also touts its SANtegrity software for providing additional security.

Courtesy the451.com