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Networking Power

Power Management and Networks? 31

Posted by Cliff from the power-management-and-peripheral-behavior dept.
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?"
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Power Management and Networks? More

Power Management and Networks?

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  • Er, to be pedantic (Score:3, Informative)

    by dasunt ( 249686 ) on Monday June 13, 2005 @04:03PM (#12805794)

    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.

    • Yes, you are right there. Even when 'off' the NIC and the motherboard draw some power (3W to 5W) to support network wake-up. For the survey, the 'off' PCs were not considered to be in low power states.
  • I never use power management, except for turning off my monitor after about an hour. There are too many applications that freak out during powersave, especially ones that try to access the hard disk for various reasons. Think about it: how often do programs you write have extra code in them for handling power-save modes? Probably not many. So when your application tries to get info to/from a powered off hard disk, swap partition, etc., it many times freaks out (especially 3D accelerated games in the mid

  • Partially... (Score:3, Informative)

    by It doesn't come easy ( 695416 ) * on Monday June 13, 2005 @04:10PM (#12805873) Journal
    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.
    • Same here. Computers are configured to default to no screen saver, but the monitor goes in power save after 20 minutes idle. The hard disk goes to sleep after 3 hours of idle time. We don't want the computers to sleep completely, as we often use idle desktops as batch processing machines.
    • Do hard drives actually spin down under XP? (or NT or 2K or a Linux?) I've had that power saving feature set on my laptop and desktops for years. I don't think that I've noticed a hard drive get a chance to spin down in anything more recent than the late 90's and Windows 98. There are so many background tasks that seem to prevent that bit of power savings...
      • I haven't tried the MS systems, but on Linux they *can*. It isn't always easy, as you said background processes usually keep my laptop's HDD from ever spinning down.

        My server, though, does spin down as I have it fairly stripped down. The (software) RAID array drives can spin down, even if the main OS drive doesn't. Of course once I proved that I could do that and the system wouldn't freak out waiting for the drives to spin back up I started wondering about the relative merits of doing that. Is the wear

  • You bet power management is disabled... (Score:4, Informative)

    by Cecil ( 37810 ) on Monday June 13, 2005 @04:12PM (#12805899) Homepage
    If power management is disabled, what prompted you to do so?

    Some of them are servers. The rest run Folding@Home [stanford.edu].

    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.

  • We don't do it (Score:3, Insightful)

    by akmolloy ( 686919 ) on Monday June 13, 2005 @04:17PM (#12805969)
    I manage about 500 Workstations, all Dell running XP.

    We schedule our WSUS (MS Software update services) to run at night so as not to bother the user. We also run quite a few machines with Deep Freeze, and they require a "Maintainence Mode" in order to unfreeze and apply updates.

    My Staff are also becoming addicted to running Remote Desktop, so they won't let us control when the machines are turned off.

    Most new staff ask me what they should do with their PC at night, and I always feel guilty when I tell them that it doesn't matter to me, and they might just leave it on. (Even if they turn it off, it auto-ons itself at 4:00 a.m.)

    • Thanks, have you tried enabling and using wake-on-LAN in the PC network cards to wake-up the PCs for the software updates?
      • Never tried that, altough that might be something to consider, but then to write a batch script to run and wake them all up requires knowing all of their MACs, etc, which we don't currently keep close tabs on. Maybe when it hits me how wasteful I'm being it'll be worth the work, but for now it seems like a high cost:benefit ratio.

        • Re:We don't do it (Score:2, Interesting)

          by sharkey ( 16670 )
          With 500 PCs, MS SMS might be worth looking into. I'm looking at the SMS Wakeup from E1 right now, since I can't keep these wonderful people from turning off their PCs. SUS got to be so unwieldy, when we upgraded to SMS with the Update stuff it was a huge relief. Never tried WUS, it was vapor for over a year before we upgraded.

  • Always Using my CPU (Score:3, Informative)

    by justanyone ( 308934 ) on Monday June 13, 2005 @04:18PM (#12805975) Homepage Journal

    I'm always using my CPU, so I don't want it to go into low power mode. I support the Folding At Home [stanford.edu] and IBM's World Community Grid [worldcommunitygrid.org] 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.
  • I grew up with MS DOS 3.3 and progressed until Widoze 98 and then switched to GNU/Linux. I had a period whith 98 where I wanted to test power saving, but it always made the programs and network unstable or useless. So I don't use it... besides the few seconds that it takes a computer to "come back to life" and then to be rebooted is not worth my time when I need my computer... and with encrypted wireless pcmcia it is utterly useless.

    But there are some good in the screen controll, but I need the screen to b

  • At my job, we have all the servers & workstations configured to run 24/7, for several reasons.

    On each computer, scheduled jobs (cronjobs on Linux & OSX, scheduled tasks on Windows) do things like backups, updates, antivirus & antispyware scans, etc. Making these things happen automatically and outside of business hours makes life much easier for the people that have to maintain all these systems (i.e. me). The main downside is that occasionally an operating system will force an unattended, unprompted reboot, causing the owner of that workstation to lose work. This is annoying, but we warn people in advance that it could happen, and they need to save their work before going home; the alternative -- manually finding out about & doing these updates machine by machine -- just isn't tenable.

    The other benefit though is that we have SNMP monitoring of all hosts throughout the day. If a machine is having a hardware problem -- say, the printer is running out of toner, or someone's hard drive is filling up -- we get alert emails about it so that the problem can be fixed. This also allows us to know what machines are down at any given time, and have a reasonably small window indicating when it went down and when it came back up; this can help narrow down time frames for events like office power outages or, should it happen, the theft of a workstation.

    I suppose we could get some of these benefis while also providing nightly downtime, but the benefits of having continual monitoring & maintenance are strong enough that there hasn't been a lot of call for it -- and when someone brings the idea up, the proposal usually gets shot down by the people managing the network.

    If it were possible to bring this equipment into some kind of standby mode where it was still possible to do basic network tests (continually pingable, occasionally query for things like disc space, once-nightly wake up for updates & virus/spyware scans, etc) then maybe the idea would fly, but as things are now, there doesn't seem to be a good way to get these benefits other than by just leaving everything on all the time.

    If nothing else, at least the monitors get turned off when they go idle...

    • Thanks, have you tested using wake-on-LAN or directed packet wake-up to periodically wake-up PCs for system updates and monitoring?

      • To be honest, no, not least because we have such a mix of hardware & software (a pretty even split among Debian Stable [Woody], Windows 2000, OSX 10.3/Panther, plus some oddball Windows XP, RedHat, and Solaris machines).

        Would these things work across such a mix? I was assuming that it would be too much trouble to bother with, but maybe I'm wrong...

        The limited testing of done -- say, trying to ping or ssh to a sleeping Mac that had been configured to "wake on network administrator access" -- has nev

        • 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 [towson.edu] and MS reference. [microsoft.com]
          • i could be wrong, but i'm pretty sure magic packets don't route: they broadcast. this'd reduce the usefulness considerably in a corporate environment...
            • Unless you route them, of course. Cisco can route or block directed broadcasts. If you allow them, you can wake up PCs in remote subnets using magic packets. Watch out for increased traffic though!!

              Another solution is to have a PC on each subnet designated as the "wakeup machine". Install $WOL_UTILIY on each, then send out the packets local to each subnet.
        • Have you been to http://www.grc.com/freepopular.htm [grc.com]? 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.

          • I hadn't seen that, but it sounds like it wouldn't help. On a network of maybe fifty desktops and fifty servers, I can think of two XP machines, both of which are just there for QA work.

            Now if it worked on Windows 2000, that would be something, and if it could wake up to run Adaware / Spybot / AV scans it would be something, and if it could do all of this remotely it would be something, and if it could manage responding to SNMP queries it would be something. And if it worked on OSX or Debian, then it wou

  • Certainly there is too much software that's either not sleep-savvy or just sleep-broken. But that doesn't mean you can't do anything.

    First, set the displays to sleep. That's easy and saves plenty of energy, especially with CRT's..

    Next, set the machines to sleep that can do it well. I set all the Mac workstations to sleep, they handle things well. Linux and Windows machines depend on the hardware and how well it sleeps.

    Keep this in mind for your ongoing infrastructure plans. The more you centralize d
    • The savings from reducing night-time PC energy consumption is estimated by the LBNL to be several billion dollars. Plenty of barrels of oil there! What kind of 'broken' apps did you come across when enabling sleep?

    • Then think of the amount of energy resources that could be saved if everybody did this. I must number in the billions of barrels of oil. Maybe Homeland Security should be in on it. :)

      Actually I think that's under the jurisdiction of the Ministry of Plenty. Course the Ministry of Love (MS) will have APM 2006 with screens that can't be disabled and watch you at all times to ensure your participating properly in full compliance with the law and the principles of EngSoc (DRM/TPM), so that should make ever

  • I've been putting my desktop to S3 sleep every night for the last year or so. Overall, it works really well.

    My machine is an Intel 845BEG desktop board running FreeBSD 5.4-STABLE. The ACPI support in FreeBSD is quite good. I bought the motherboard specifically to be able to suspend it. I reasoned that because Intel pushes ACPI, they would have a good implementation in their BIOS.

    The one application I have problems with is kmail. After a resume, it will think it lost connectivity to the pop server and

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