Page 146 -

7: The Need for Standard IT Energy-Use Metrics 111

servers by different manufacturers indicate this high power use, even when
the server is doing nothing. To look at power consumed when the server is
doing nothing, take a look at the Active Idle row in Figures 7.1 through 7.4.
For example, in Figure 7.1, the server at 100 percent load uses 260 watts,
while in idle, the server still uses 187 watts (72 percent of the power at 100
percent load). Figure 7.2 shows the server using 143 watts at idle versus 244
watts at 100 percent load or still 59 percent of the maximum power use
when the server is not doing anything.
The server power tools discussed in Appendix A, “Green IT Checklist and
Recommendations,” also indicate significant server power use at idle. One of
the advantages of server virtualization discussed in Chapter 6, “A Most-
Significant Step—‘Virtualizing’ Your IT Systems,” is that server idle time is
reduced on a physical box if the box is configured to house six to ten virtual
servers. The virtual servers on a physical server can be chosen so that idle
time will be minimized. Also, manufacturers are starting to enable servers to
optionally go to sleep mode at night or on weekends when not in use. This is
similar to the options most of us have for our laptops where we can choose to
have the monitor power go off after 15 minutes of idle time or the CPU go to
ptg
“sleep” mode after 30 minutes of idle time. These power options were not
previously available on servers, mostly because energy conservation was not a
significant concern for manufacturers. Our options for laptop power options
were primarily there to automatically conserve the limited battery power we
have when mobile. For laptops, energy conservation was just an automatic
side effect.

Server Sleep Mode
In August 2008, Intel announced a new power-saving technology called
Remote Wake that lets outfitted computers doze in a power-saving mode
until an appropriate message is received over the Internet, either via a VoIP
®
call or another messaging medium. Although the Wake on LAN protocol
has been around for some years, allowing computers with the right Ethernet
card and software to monitor a network even while sleeping, Remote Wake
goes far beyond that.
Remote Wake needs to maintain a persistent network connection with a
central server to function as Intel intends, as most computers in homes are
behind Network Address Translation (NAT) gateways that prevent direct
access. It’s possible that a combination of UPnP (Universal Plug and Play)