According to Cassatt's director of product management Ken Oestreich, powering down servers can be a safe, viable activity. Moreover, the company practices what it preaches. "We've got several hundred servers here that we're power managing that are turned on and off several times a day. We've had no failures for three or four years," he said.
He argued that servers have the resilience to be powered up and down on a daily basis in their useful life. "If you assume that the average piece of equipment has a three- or four-year depreciation cycle, and you cycle it once a day, you're talking about one or two thousand power cycles for the lifecycle of the machines. That's actually not a lot," said Oestreich.
Cassatt isn't the only company dabbling in shutting down servers. Cisco is doing a pilot program at its two datacenters of an in-house application called V-Frame, a management app designed (among other things) to elegantly shut down servers in batches remotely, similar to the way a remote server management system shuts down a single server.
According to Rob Aldrich, director of datacenter solutions at Cisco, V-Frame has the capability to address the problem of a server not shutting down completely when the OS hangs: Admins can cut off power to the server from the power rails at the back of the rack, via IP. "It's nice to have the added benefit to know you can cycle the power physically ... and do a hard reboot if you need to," he said.
Cisco is testing the application on only 200 of its 10,000-plus systems, targeting production servers that don't need to be used all the time. "For CRM, we have certain groups of servers that deal with network attached storage archiving which get shut down after a period of inactivity," said Aldrich. "On our file and print servers ... we shut those down after 8 p.m. in the evenings and on weekends. For batch payroll processing, we only spin those up during our processing periods for payroll."
The company has been pilot testing V-Frame for three months, and according to Aldrich, there've been no major problems or complaints thus far from IT.
The company isn't too worried about the impact of temperature cycling on the hardware it's powering down. "When you're refreshing servers every five years at most, it's a risk we're willing to take. We don't think the hardware is going to be adversely affected within the constraints of our refresh cycle," said Aldrich.
Aldrich noted that one of the biggest barriers to shutting down servers is getting buy-in from all parties concerned. After all, if your job depends on application reliability, you might be hesitant to take chances with servers being powered up and down. But the potential payback of lower energy bills and even, possibly, more capacity might make it more palatable.