No Wake-On-LAN for powered-down Macs?

I'm relatively new to Mac and don't have a lot of Mac experience or knowledge. Last week I completed the "Mac OS X Deployment v10.4" training in Sydney where the trainer told me that Wake-On-LAN will only work if the Mac in question is in sleep mode -i.e., you can't wake up a Mac that has been shut down. Is this really true?

As an administrator of Windows machines this seems like quite a shortcoming. From where I am sitting I can rebuild any room of computers in any town in my area of control (an area greater than 100,000 square kilometres in NSW, Australia) without having to be there physically to turn on the PCs. At the moment our two Mac rooms are located at my own site, but without Wake-On-LAN, there's no way I could see Macs being deployed anywhere else.

If Wake-On-LAN really does only work with Macs in Sleep mode, then how much power does a 20" Intel iMac draw when in Sleep mode? I really don't like the idea of setting a schedule for every Mac to turn on at a certain time then have them go into sleep mode each and every day on the off chance that I might want to rebuild just one of them. This seems like an awful waste of power to me.

Don't get me wrong, here. I'm not trying to flame because I'm very - very - impressed with Mac in almost every other respect (except the Finder and the Dock) and would switch to Mac long before I stomach Vista, but no Wake-On-LAN to me seems like an incredible stumbling block to Mac adoption.

Intel iMac 20" Mac OS X (10.4.9)

Posted on Apr 26, 2007 8:15 PM

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12 replies

Apr 26, 2007 8:38 PM in response to Homercycles

"Is this really true? "

Yes. I doubt the trainer would lie to you.

Are you really that worried about power consumption? Do you regularly just decide to rebuild a computer on a whim as you suggest?

"As an administrator of Windows machines this seems like quite a shortcoming."

Don't tell us, tell Apple:

http://www.apple.com/feedback

"but no Wake-On-LAN to me seems like an incredible stumbling block to Mac adoption"

That's your opinion. I support over 1000 Macs from San Francisco to New York, London and Frankfurt, and it's never been an issue.

Apr 26, 2007 10:32 PM in response to Templeton Peck

Are you really that worried about power consumption? Do you regularly just decide to rebuild a computer on a whim as you suggest?

The more Macs we potentially get then the greater is the power consumption if they're all booting on a schedule only to go into sleep mode. Most of Australia's power comes from coal so needlessly burning more coal to compensate for Mac's lack of Wake-On-LAN is pretty bad, in my view.

If somebody logs a request with the name of their Mac saying that it needs to be rebuilt and I get it a day or two later, then I can't rebuild it if it's switched off like I can with a PC. I have to ring somebody up and ask them to walk to wherever the Mac is and ask them to turn it on. I'm not going to look forward to this as standard procedure if we get more Macs in remote locations.

That's your opinion. I support over 1000 Macs from San Francisco to New York, London and Frankfurt, and it's never been an issue.

Yes, it is my opinion, but the opinion of IT support usually counts when it comes to the question: "should we go Mac or Windows?" It may not be an issue for you - perhaps you're OK with ringing people to get them to turn machines on - but it definitely will be a problem where I work if we get Macs at locations where there is not an IT support officer.

Intel iMac 20" Mac OS X (10.4.9)

Apr 27, 2007 7:41 AM in response to Homercycles

Mac's lack of Wake-On-LAN is pretty bad, in my view.

Just to be clear, Macs do have Wake-on-LAN. What you're asking for is BOOT-on-LAN, and that Macs do not have. I don't know how many PCs have this feature, but those that do must continue to have parts of their circuitry awake, which probably draws almost as much current as a sleeping Mac.

how much power does a 20" Intel iMac draw when in Sleep mode

Around 5 to 7 watts.

Apr 27, 2007 6:24 PM in response to varjak paw

Trying to find hard facts on the power used by Wake-On-LAN is pretty hard, it would seem, but I did find a comparison* of power usage made by the IT department at the University of Canterbury in New Zealand. They found a range of 0 to 3 watts power usage by machines "powered down" (it doesn't say for sure if all had Wake-On-LAN enabled) but the highest figure observed - 3 watts - is probably a good indicator; WOL only retains power to the network card, and doesn't have to maintain memory state, which would draw more power.

When you're talking about hundreds of computers, the difference between power usage in WOL-enabled PCs "powered down" and Macs in sleep mode begins to add up. All computers where I work have WOL and we couldn't live without it. With over 1,000 PCs alone in the department I work for, replacing them all with Macs and setting a schedule to have them wake up and go to sleep all day (all of which would use c. 100 watts or more booting up until they go to sleep) constitutes a great deal of wasted electricity.

* http://www.it.canterbury.ac.nz/resources/documents/computermonitorpower.doc

Intel iMac 20" Mac OS X (10.4.9)

Apr 28, 2007 9:11 AM in response to Homercycles

I completely understand your wanting this option. I am not sure why Apple hasn't started building it into their computers sooner-- since back to the original iMac they've been able to turn on via a button on the USB keyboard, which seems a trickier task than powering up via NIC & magic packet.

I do encourage you to fill out a feedback form as someone stated above. Perhaps Apple hasn't seen the need, but with more enterprise integration, it's a low-cost-to-build-in no-brainer.

As someone else stated, it is not a big deal to most of us. The Macs I've managed are so reliable, I haven't found a need to do much re-building. I am not discounting your opinion, just saying that once you're up and running, perhaps you'll not find the need as great as you thought it would be.

The other functionality of ARD is really great, the tools, especially the wonderful relatively unexplored world of the send UNIX commands, I think you'll be quite happy with the power you do have.

One possible suggestion for a work-around which minimizes the energy use-- set a boot time for just one day per week, perhaps different times for different groupings, and then set a schedule in ARD to connect to them at those times and run maintenance scripts and shut them down, unless you find need to do more, as you said, and you can modify the schedule accordingly.

I don't believe there is a send unix command to adjust the auto-wake settings - I have not tried, but you might on one machine, setting the wake time one day per week, then copy the file /Library/Preferences/SystemConfiguration/com.Apple.AutoWake.plist to another Mac. The file has a warning in it against hand-editing, which is why I think this approach is the only which will work. However, I would be very careful with it-- if you change the energy saver setting, for example, to turn on at 7:00 am every Monday, and then look at the file, it sets the actual date of the next wakeup, so this must dynamically update the file each week.

But WOL ("BOL," as someone clarified) would be a great addition to the platform.

Good luck.

Apr 30, 2007 4:14 PM in response to MacToeKnee

I did submit some feedback so hopefully Apple will find some way to add Boot-On-LAN (even though the PC side of the industry regards Wake-On-LAN as what Mac people seem to want to call BOL).

I'm not going to go ahead with a regular boot schedule at this point because the Macs I have to support are all at my location, which is the way it will stay until Macs support "BOL".

Yes, Macs generally are very reliable but since I work in an education environment we often have a need to rebuild Macs to support different setups and having to pull my hair out because of the lack of BOL just means that Macs won't be multiplying beyond the 32 we already have for the forseeable future.

Intel iMac 20" Mac OS X (10.4.9)

Apr 30, 2007 8:58 PM in response to varjak paw

Actually there is, through the pmset command. Read
the man pages for pmset for the syntax.


cool! I went through every command line resource I could find looking for keywords, but I didn't find anything about setting schedules, and I didn't think to check the pmset man pages.

Homercycles wrote:
...Boot-On-LAN (even though the PC side of the industry regards
Wake-On-LAN as what Mac people seem to want to call BOL).


I think someone suggested BOL above, but I don't think there's any allegiance among "Mac people" to use that term. Perhaps a better way to look at it is that "WOL' is not really an accurate term; you're not "waking" a PC from sleep or standby, you're actually causing it to power up from a powered-off status. Since Macs have had (for as long as can remember) a setting to "wake for network administrative access," and Macs use the antonym "sleep" to denote the equivalent of Windows' 'standby," the term "wake on LAN" has no chance of being understood by people who've never administered PCs anyway.

Might I suggest "remote boot?" Or perhaps "Network initiated computer bootup using magic packets" (NIC-BUMP)?

not so much

May 9, 2007 2:24 PM in response to Homercycles

I've already complained of Mac's variation from the "standard" WOL implementation. This problem goes a step deeper as I just discovered.

If in the energy saver options you check the "Restart after a power failure event", the machine will do just that. If the power fails, and then comes back, the machine will boot.

If however, you cleanly shut down the machine, and then power fails, it does not turn back on when the power recovers. All PC's that have auto-power on with AC power restored set in their bios don't care if the machine was cleanly shutdown or crashed... when power comes back, it boots.

The problem here is that when a UPS detects a power failure and eventually decides to shut down the attached computer it should do so cleanly, not by just crashing it (that defeats the purpose of having a UPS!). After the computer turns off, the UPS will turn itself off, cutting power to the computer all together. When the AC power to the UPS returns, and the batteries charge sufficiently, it will turn BACK on, and restore power to the computers.

As it stands now, I have no mechanism by which to force my Mac to boot back up! I could depend on a linux machine on the network (that does behave properly) to send a WOL packet, but it doesn't do that correctly either... so I'm SOL 🙂

I can understand having 3 options for reboot after power restore. (1. Restore Always, 2. Restore when system on and power fails, 3. Never Restore).

Only giving us options 2 and 3 is just an oversight of how computers are used in the real world. For the desktop user that may on rare occasion find his machine powered off, and just presses the power button, this is a non issue... But in my opinion this completely eliminates a Mac like this from being used as a webserver/mailserver or other application where uptime is paramount.

I can't believe that Apple would overlook something so important and not provide a mechanism by which a UPS could turn a computer back on after a power recovery. Perhaps there is a non-published setting that doesn't have a check box on a form, that an OEM UPS driver would set that says "pretend you crashed".

May 9, 2007 3:28 PM in response to RRuss

There is no way for an external device to power up any current or recent Mac other than the current Intel-power Xserve, either when the device is physically attached or via LAN. That facility just hasn't been in a Mac for a number of years now. So if a UPS shuts down a Mac, there's no way for the UPS to restart it; the mechanism just isn't in a Mac to allow it. I agree that this is a major issue in some cases, particularly servers, but it's the way it is right now, and there is no "setting" that can change it; it's just not possible unless you have an Intel Xserve.

The only workaround would perhaps be to set a startup time in the Energy Saver schedule settings. That at least would bring up a shut-down Mac at a given time so that it doesn't just sit off until someone gets around to start it back up. Or get a new Xserve, which allows remote powerons. Not a desirable state of affairs, I know, but it's just the state of Macs as of today.

You can, if you wish, provide feedback to Apple via the appropriate feedback page.

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No Wake-On-LAN for powered-down Macs?

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