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Power Management and Networks?
ChamaraG asks: "Do you enable power management in your desktop PCs, and have you had any problems with networking after enabling power management (problems like losing open network connections, network using applications hanging after resuming from low power states, etc)? To clarify, by desktop PCs I mean PCs compliant with ACPI and Wake-On-LAN and capable of resuming from low power states in a few seconds, so that waking up time is not an issue. I am interested in the energy efficiency of networks and networked devices and I would like hear of problems that you might have had. Some applications I have tested will disable power management settings, presumably in order to maintain network connectivity. Surveys by the Lawrence Berkeley National Laboratory show that less than 5% of desktop PCs in offices are in low power states at night (36% - off, 60% - on). So, do you enable or disable power management in your PCs? If power management is disabled, what prompted you to do so and what would make you enable power management? What connectivity related problems did you encounter after enabling power management?"
Considering modern ATX power supplies common to most desktop PCs, wouldn't "off" be considered a "low power state"? (ATX power supplies use a small amount of current even when the computer is off, unless the power supply is plugged.)
In that case, the stats will be that roughly 40% of desktop PCs are in a low power state at night.
For XP Home edition on Dell computer: No deep hibernation allowed (computer won't wake up), no Ethernet card power down allowed (always loses the connection and has to be restarted). Everything else seems to do ok. Monitor going to sleep is good (saves screen, saves heat, better screensaver than some silly graphic acrobatics and no wasting cpu cycles). Hard drive spin down is ok as long as it doesn't happen too fast (at least one hour of inactivity). Of course, running SETI or some other background community software means your computer can't sleep.
FYI, the statistics in the report do not include home computers.
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If power management is disabled, what prompted you to do so?
Some of them are servers. The rest run Folding@Home.
and what would make you enable power management?
Being completely unable to afford not to. We've got quite a ways to go before energy becomes that expensive.
I hate idle computers, and by definition a computer in power-saving mode is idle.
Random and weird software I've written.
I'm always using my CPU, so I don't want it to go into low power mode. I support the Folding At Home and IBM's World Community Grid projects.
Even if I wasn't, I'm often still using my CPU for keeping Azereus running (Fedora distros).
I don't want it going offline. I want it doing my bidding full time.
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Wake on LAN is primarliy a NIC/driver/motherboard issue. From what you are saying, your PCs support it, but you are not sending the right kind of wakeup call. When a PC that's in standby or "off" receives a magic packet (which is what I've looked into), a wake up frame or the link state changes (depending on what you set it to do), the PC turns on. (getting them to standby/sleep reliably is harder. WoL can usually be handled without the OS) Check out magic packet info and MS reference.
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"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
Have you been to http://www.grc.com/freepopular.htm? One of his tools, Wizmo (for XP), is accessed from the command line and can do a variety of things with a simple command(including sleeping and hibernating a machine, among other things. It's not a big app either.