Published: 09 Feb 2005
|Common SAN designs|
There are many possible design possibilities when creating a storage area network (SAN). Josh Judd, author of Multiprotocol Routing for SANs, identifies the most common SAN design options.
The need for SAN design automation is clear. "As soon as you go beyond a SAN that is small--maybe one switch and a few devices--you can't design it with paper and pencil, a spreadsheet or a whiteboard," says Bill North, director of research, storage software at International Data Corp. (IDC). "Everything just breaks down."
For most organizations, expanding a SAN is a trial-and-error process. SAN design projects rarely start with a blank slate; instead they expand or consolidate storage that's in place. Storage managers need to decide what works with what and how best to connect all the SAN parts together.
Outside consulting firms are frequently brought in to design a company's SAN. They navigate the minefield of interoperability considerations and constraints, document the resulting SAN environment and train staff to maintain it.
Regardless of how well planned and designed the SAN may be, it will invariably change. Keeping track of what you have, matching compatibility among components at every layer of the protocol stack, and ensuring everything is connected correctly and that redundant links are where they need to be becomes a labor-intensive task. Lack of up-to-date SAN documentation makes the job even more difficult.
"You need a way to design [the SAN], automatically discover what is there and [then be able to] compare it to what you planned," says North. This requires an automated SAN design tool.
To date, only two vendors offer SAN design tools: Computer Associates (CA) International Inc. has its BrightStor SAN Designer, while EMC Corp. provides SAN Architect. In addition, Boston-based Onaro Inc. offers SANscreen, a SAN change management tool (see SAN design tools). "That's about all [the companies] that do SAN design," says Randy Kerns, senior partner at the Evaluator Group Inc., Greenwood Village, CO. However, there are numerous vendors with storage resource management (SRM) and SAN management tools that offer various levels of automated device and topology discovery.
"You'd think there would be more SAN design tools, but there aren't," says Kerns. CA and EMC acquired their SAN tools from two small vendors, Netreon Inc. and Prisa Networks, respectively. "Tools like these should probably be integrated into bigger SRM and SAN management solutions," he adds. CA has made BrightStor SAN Designer a component of its larger BrightStor SAN management suite, while EMC offers SAN Architect as part of its ControlCenter family.
Although part of BrightStor, SAN Designer can be purchased as a standalone product, reports Eric Pitcher, director of CA's BrightStor product management. The tool incorporates a storage knowledgebase that contains product interoperability and compatibility data from all major storage vendors and also includes Visio, a popular graphical diagramming tool.
SAN Designer and Visio enable a storage admin to connect the elements of a SAN, with SAN Designer's knowledgebase providing alerts of impending interoperability problems. "SAN Designer knows what the object is, checks the certified device list and can tell you if it will work," Pitcher explains. The product also identifies vendors, models and firmware.
Another component of SAN Designer is its automated discovery engine, which searches the storage network, reports what's connected and automatically documents its findings. A built-in set of best practices makes design and deployment recommendations, and even identifies which devices should be plugged into which ports and in which order.
Finally, the product's impact analysis capability lets storage admins simulate changes, conduct what-if analysis before implementing anything and alerts them to problems.
For Todd Pekats, a former SAN designer and now director of storage alliances at Dallas-based CompuCom Systems Inc., the biggest value of SAN Designer is the up-to-date documentation it generates. CompuCom, a CA reseller and systems integrator, uses SAN Designer when it develops SAN designs for its customers.
"The SAN is constantly changing, so any manual documentation is quickly outdated. When a problem occurs, there's always a scramble to get the right data before you can begin to fix anything," says Pekats. SAN Designer captures all changes to the SAN--devices, ports, software, firmware and switches--automatically.
When documenting a SAN, SAN Designer generates a parts list and wiring diagram. The discovery is useful when extending an existing SAN. "Most of our customers use the major vendors and common equipment. For that, the discovery works very well. If there are a lot of one-off products or old products, it might not be able to identify everything, but for us it's accurate enough," says Pekats.
SAN Designer is $2,700 per seat, with one year of maintenance and downloadable knowledgebase updates.
|SAN design tools|
EMC takes a different approach with SAN Architect. The tool is currently offered only as a Web-based subscription service, but it may be introduced as a loadable product in 2005, says Barry Ader, EMC's director of enterprise software. Pricing for a one-year subscription starts at $2,400.
The key component of SAN Architect is its interoperability matrix, which is similar to CA's knowledgebase. SAN Architect uses the interoperability matrix to identify which components of the SAN will work with other components. In addition, the tool provides a set of best practices consisting of as many as 150 design rules. "These are recommendations about the placement of cards and the configuration of various pieces," says Ader.
Currently, SAN Architect lacks automated discovery. "The administrator enters the details [using a Web browser] of the design manually," Ader explains. Once the details are entered, the admin can run an interoperability screening. EMC expects SAN Architect users to render the final results of their design with Visio, although Visio isn't built into SAN Architect as it is with the CA product.
EMC plans to integrate SAN Architect with its ControlCenter SRM tool. At that point, configuration data stored in ControlCenter will be shared with SAN Architect. The product was in beta at the end of 2004, and Ader expects the integrated product to be available in early 2005.
Matt Steinberg, senior solutions architect at systems integrator and EMC partner Cambridge Computer Services Inc., Waltham, MA, uses SAN Architect with customers. "We use it mainly for help with compatibility through the interoperability matrix," he says. For example, it saves him from sorting through vendor certification lists to discover which host bus adapters work with which hosts.
Although the interoperability matrix contains data on a wide range of vendors' SAN components, the tool is intended primarily for SANs designed around EMC arrays.
In SAN design, the initial SAN is the easiest because it just happens. "Usually people don't design a small SAN. They just plug together a switch and a disk array," says Josh Judd, author of Multiprotocol Routing for SANs and principal engineer at Brocade Communications Systems Inc. Design issues crop up when you change or add to the initial SAN. That's when it gets complicated (see Common SAN designs).
"Every change has to be designed with regard to best practices," says Assaf Levy, VP of product management and co-founder of Onaro, which offers SANscreen (for a review of SANscreen, see Storage, September 2004). SANscreen lets admins simulate changes to the SAN before they're implemented. It then produces impact reports highlighting the results of the contemplated changes.
SANscreen also does SAN discovery, although it lacks the vendor-specific compatibility knowledge built into SAN Architect and SAN Designer. Instead, it identifies the SAN components and their dependencies, and then tracks and documents any changes to the SAN.
As SAN design tools evolve and discover more devices in the SAN, they'll become more useful. Interoperability issues consume a storage admin's time. Changing the SAN's configuration is their biggest design challenge.