iMac - Slow to sleep

[mebwm]

My desktop iMac SS 10.6.4 2GB ram and 163GB available space on the HD used to go to sleep as soon as I selected sleep down under the apple now it takes at least 30 seconds. Is there a setting to correct this or is it a sign of impending problems?
Thanks
Mary

[Dan Millar]

Hi Mary,

Welcome to Mugoo! Sorry to hear you're having issues with your iMac. Faulty sleep behaviour is one of those small, but irritating issues, and should be simple to fix, once you determine what has caused it. Its the determination that's the tricky part.

It may be account-specific - try logging in to your Guest account. If the problem recurs it is systemic, if not, it is something specific to your account.

External hardware and its software can be real culprits here. Start your Mac with nothing attached but the keyboard and mouse/trackpad, and hold down the shift key from the time you turn on the Mac until the login screen appears. You should see a message in red on the login screen that tells you you are in "safe mode". Login to your account and test it. If your Mac sleeps normally, then one of the external devices or its software is causing the problem.

Let us know if this helps and we can try some solutions.

Happy Mac'ing!

Dan

[z-mac]

Print jobs that are stuck in the print queue can also delay the activation of "sleep".

[ben schmidt]

My desktop iMac SS 10.6.4 2GB ram and 163GB available space on the HD used to go to sleep as soon as I selected sleep down under the apple now it takes at least 30 seconds. Is there a setting to correct this or is it a sign of impending problems?
Thanks
Mary

There are actually two types of "Sleep" on a Mac:

• Hibernate [default]: write the RAM contents to a disk file. This does not depend on power, and hence survives Power interruptions.
• True Sleep: Skip writing to disk but keep a trickle of power running inorder to keep RAM contents safe. This is faster as there's no writing to disk, but will not survive a power interruption to the Mac, as that would wipe out the RAM contents.

Since your Mac is configured to use the first type, Hibernation, by default, it's possible to speed up Going-to-Sleep by switching it to the 2nd type. This is not something that most users ever touch, but if you're curious, you can switch your Mac back and forth between these two settings, with no harm.

There are utilities to do this switching for you, or it's possible to walk you through this using a couple of commands into terminal.app in your Utilities folder. For those who want the sordid details, the inimitable Rob Griffiths, MacWorld columnist, and founder of osxhints.com has the details here: Set newer portable Macs' sleep mode

...ben

[Dan Millar]

Desktop Macs do not hibernate, as far as I know. Please correct me if I'm wrong, as I just checked a series of Macs, from G4 PMacs to this year's iMac 27, and the desktops are all set to mode 0 - quick mode, while the portables, which range from G4 PowerBooks and iBooks to this year's MacBook Pro, are all set to Mode 3 - safe mode.

There are actually three different ways your Mac can sleep - Quick, Safe and Deep (also something known as "Dozing"-another topic).
Quick mode powers off everything but RAM, consuming little power, and making sleep/wake-up very quick, but not immune to power failure.
Safe mode writes RAM to HD, but keeps some power to RAM, slower to sleep/wake, and immune to power interruption/failure.
Deep mode writes RAM to the HD, and powers everything off - making it slowest to sleep/wake up, but immune to power interruption.

Most desktop Macs, including the latest crop of desktop iMacs, use Quick by default. Most portable devices will use the Safe mode, allowing batteries to be changed with little interruption. Deep mode is not normally available, but may be added through the use of a utility like Deep Sleep, or, gasp, the Terminal. iPad does Deep mode, and AFAIL only the new MBAirs can do this as well.

If the OP - mebwm - had changed that setting, then yes, it could affect sleep time on his iMac. However, he stated that the Mac slept quickly previously, but had recently begun to slow down the process. Many things can cause this, stuck jobs in printer queues being the most common, but internet connections, external wired and un-wired devices, etc. can also be the culprits.

We never heard back from the OP, so it's hard to say if we solved his problem, or just over-complicated it!

Happy Mac'ing!

Dan

[ben schmidt]

If anyone would like to play with their Mac's sleep/hibernate settings, but is shy of the using /Applications/Utilities/Terminal.app, here's a free Preference Pane:

  http://www.jinx.de/SmartSleep.html

I tried it out on my unibody MacBook Pro running OS X 10.6.5 and it seems to work, as confirmed by running the following command line from terminal.app: pmset -g | grep hibernatemode

For testing purposes the SmartSleep setting: "Sleep Only" should give one the fastest possible sleep.

...ben

[ben schmidt]

As an experiment, I've used the SmartSleep preference pane to set my MacBookPro 4GB to "sleep only". That means it skips writing writing a 4GB RAM file to disk when it sleeps. Or as Dan mentioned, this is equivalent to hibernate mode zero, viz this command-line entry into /Applications/Utilities/Terminal.app:

      sudo pmset -a hibernatemode 0

My MacBookPro now goes to sleep much faster now that it does not have to write a 4GB file to disk every time it sleeps. The downside is that if the battery drains completely while sleeping, or if I change the battery (I have the last MacBookPro model with the swap-able battery) - the RAM contents will not be preserved.

Encouraged, I also set my MacBookPro not to wake on lid opening. On several occasions, I've pulled my "sleeping" MacBookPro out of my backpack only to find it toasty and still running, or even completely battery-dead. I've surmised that somehow the lid inadvertently opened in transit enough to "wake" it.  Now My Mac does not wake on lid opening. Rather I open lid, and have to hit any key to wake it.

      sudo pmset -a lidawake 0

...b

PS. To learn about related settings, enter the command-line man pmset into terminal.app