Interoperability and testing hurdles
Despite vendor claims of non-disruptive upgrades, it's painfully clear from these accounts that many users suffer operational disruptions when loading new microcode. ESG's Duplessie lays the blame squarely on vendors not performing enough regression testing of production environments. "When it works in the lab, it doesn't always work in the real world with all the interdependencies that exist," says Duplessie. "Users should never assume that non-
disruptive means non-disruptive to them, only to the vendors."
To be fair, vendors would never introduce a new product if they tried to test it against every possible scenario. "The reality is that with thousands of customers, all with unique environments, we test as much as we can but we can't get everything," says Chris Bennett, senior director of product management at Network Appliance Inc.
And some vendors readily acknowledge that early product adopters are guinea pigs. In fact, HDS customers are contractually precluded from running beta code in their production environment. "Most customers hold to that," says Claus Mikkelsen, chief scientist at HDS. "They get special attention, insight and education from the vendor, and they get to deploy it a lot sooner," which is why many take the risk.
Upgrading directors
According to Duplessie, core switches are updated more frequently than anything else these days as more intelligence moves into the fabric. Cisco Systems Inc.'s MDS directors support what in networking is called hot-code activation. A close read of Cisco's configuration guides reveal that its directors have hot-code activation for Fibre Channel ports, but not for IP ports. IP Storage Services modules use a rolling-upgrade install mechanism where each module in a given switch can only be upgraded in sequence. To guarantee a stable state, each IP Storage Services module in a switch requires a five-minute delay before the next IP Storage Services module is upgraded.
Similarly, Mario Blandini, product marketing manager at Brocade Communications Systems Inc., acknowledges that during a non-disruptive firmware upgrade there's a short pause in management operations (e.g., new devices being authenticated) while new software is activated. "Switching traffic continues to flow throughout the activation and management operation, and processing resumes once the activation is completed," says Blandini. He likens non-disruptive code upgrades to "keeping people awake during brain surgery ... it's possible today," but still risky.
Still, the impact of taking hundreds of ports offline for an upgrade is unacceptable to many organizations. And the consensus among analysts is that as the world continues to move toward 24/7 operations, the need for truly non-disruptive upgrades will be mandatory.
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