"The hot aisle is just too hot," Sacco said. "If you're going to exceed 110 degrees, you could actually exceed the [National Electric Code] standards."
Forgetting about the fire code issues, Menuet added that you have to think of your employees.
"It will be over 100 degrees in the hot aisle," he said. "It certainly isn't comfortable for technicians that have to get in there and work on the equipment."Using vinyl curtains for separation
Using vinyl sheeting, much like what you'd find in a meat locker, is one method that data centers have used to contain their hot aisles. Storage vendor NetApp uses them and says the curtains alone save it 1 million kWh of energy per year. Yahoo uses them in one of its data centers as well.
But there are fire suppression issues with this method as well. If you have plastic sheets over your racks and don't have sprinklers in the contained area, how can a potential fire be squelched? Most companies that manufacture this sheeting say it melts at 130 degrees, thus eliminating the aisle containment and allowing the sprinklers to work from there. But what if for some reason the curtains malfunction?
"The curtain attaches to the ceiling with heat-sensitive fusable links," Menuet says. "If there's a fire, the heat melts the links and the curtain falls. But if I was the fire marshal, I'd be concerned about a curtain hanging from some fusable links. Most places would have trouble with that. If I were proceeding with good hot-aisle/cold-aisle containment, I would design a fire system around it and put enough heads in the hot aisle and enough in the cold aisle."
Never mind the aesthetic ramifications. Menuet said he was working on a project in Minnesota, where discussion included using freezer curtains to contain the hot aisle, "but it didn't show well." In other words, company executives might not like the fact that their data center looks like the back of a butcher shop.
Inform the local fire inspector
Sacco added that one of the most important things is being in line with local fire authorities, because if they conduct an inspection, see something they weren't notified about and don't like it, they could shut you down.
"Many people deploy these systems in ignorance of the law," he said. "Many people do it and manufacturers are manufacturing the pieces. But the local inspector is the final authority. If the local inspector doesn't realize what's going on, the whole job might not be compliant."This last statement is worth remembering when you are tinkering within your data center.